Everything That's Gone Down Between Britney and Jamie Lynn Spears Since the "GMA" Interview

While promoting her "Things I Should Have Said" memoir on "Good Morning America," Jamie Lynn spoke out about her relationship with her older sister, the pop star's conservatorship, and two alleged incidents where she was "fearful" of Britney.

"It's important to remember that I was a kid in that moment. I was scared. That was an experience I had. But I also was fearful to, like, really say anything because I didn't want to upset anybody or anything," Jamie Lynn said, alleging that Britney once pulled out a knife and locked the two in a room.

In regards to Britney's conservatorship, Jamie Lynn said she understood very little about it. "I was happy . . . when it was put into place, I was a 17-year-old, I was about to have a baby, so I didn't understand what was happening, nor was I focused on that," she said. "I was focused on the fact that I was a 17-year-old about to have a baby. I understand just as little about it then as I do now."

But despite their complicated relationship, Jamie Lynn remained adamant that "that love is still there, 100 percent." She added, "I've only ever loved and supported her and done what's right by her, and she knows that, so I don't know why we're in this position right now."

In a series of Notes App screenshots, Britney addressed her younger sister's "GMA" interview, claiming that Jamie Lynn was using her to promote her book.

"Anyways, the 2 things that did bother me that my sister said was how my behavior was out of control. She was never around me much 15 years ago at that time .... so why are they even talking about that unless she wants to sell a book at my expense ???" Britney wrote.

Britney also referenced Jamie Lynn's tribute performance at the 2017 Radio Disney Music Awards, where Jamie Lynn covered "Till the World Ends." "I know it may sound like a silly thing to most people but I wrote a lot of my songs and my sister was the baby," she added. "She never had to work for anything. Everything was always given to her !!!!"

She concluded with: "Hope your book does well, Jamie Lynn !!!! . . . My family ruined my dreams 100 billion percent and try to make me look like the crazy one . . . My family loves to pull me down and hurt me always so I am disgusted with them !!!"

In a follow-up post, Britney called her sister out for stooping to a "whole new level of low." She tweeted, "I've never been around you ever with a knife or would I ever even think to do such !!! The only knife I ever saw you with at home was cutting the biggest pieces of squash I ever saw in my life and it was way too big for me to cut ... So please please stop with these crazy lies for the Hollywood books !!!"

She continued, "NOW and only NOW do I know only a scum person would make up such things about someone.... I'm actually very confused about you making that up because it's honestly not like you at all!!!! Around the kids???? Jamie Lynn, seriously??? Come on!!! Congrats on introducing your older sister the concept of getting LOW... LOWER... LOWEST... because you win on that one, babe!!!!"

Jamie Lynn shared a letter response to Britney via Instagram. She began, "Last thing I want to be doing is this, but here we are... It's hard to see these posts, as I know the world also feels. I just wish her well. Brit, I am always here, you know behind the scenes I have always been here."

Jamie Lynn acknowledged that she understands that Britney is "going through a lot" right now, but she can no longer "diminish" herself. She added, "The things being said are absolutely not the truth, and I have to clarify that, because now it's getting harder for me to rationalize to my oldest daughter why our family continues to get death threats, as a result of their aunt's vague and accusatory posts, especially when we know she could tell the truth, and put an end to all of it in one second if she wanted to."

She also shot down Britney's accusations of using her sister for profit. "I hate to burst my sister's bubble, but my book is not about her. I can't help that I was born a Spears too, and that some of my experiences involve my sister. I've worked hard since before I was even a teenager, and I've built my career in spite of just being someone's little sister," Jamie Lynn wrote. "There are no sides, and I don't want drama, but I'm speaking my truth to heal my trauma, so I can close this chapter and move forward, and I wish my sister could do the same. No matter what comes, I will always love my big sister, and be here for her. It's time to put an end to the unhealthy chaos that has controlled my life for so long."

In another series of Notes App screenshots, Britney wrote an open letter to Jamie Lynn. She began, "Jamie Lynn ... I don't think your book is about me at all ... I said some harsh things because you obviously hurt me by the things you are making up about me !!!"

Britney then accused Jamie Lynn of not doing enough to help end her conservatorship. "I think the thing that saddens me the most is that when this all happened to me and when I called you from that place ... you would take days to respond !!! You would just text me days later and I was so scared ... I needed you ... my family, my blood and you guys did absolutely nothing UNTIL a year ago !!! I said something on Instagram and you and Bryan showed up at my house ... because of an Instagram post !!! THAT makes me the saddest," Britney wrote.

She ended her note with: "I don't care anymore !!! Say whatever you want to say just know I do know your real heart more than anyone !!! It's your life and you deserve a beautiful life !!!! I wish I would be able to do what you're doing and do interviews !!! I'm scare of all of it ... I admire you for being strong ... just know I love you and I think you know that already more than anything !!!."

While promoting her book on the "Call Her Daddy" podcast, Jamie Lynn once again talked about her complicated relationship with Britney. "I love my sister. I'm her biggest fan — but guess what? Sisters are sisters, or whatever, you know?" Jamie Lynn said. "I was born into this family. I didn't choose this. It's like, imagine, like, a big ship and I'm like just a little, like, dinghy riding in the waves like, trying to, like, f*cking survive, you know? And, so that was my life was like — just survive this moment."

Jamie Lynn also brought up the alleged knife incident again. "I think people need to remember, I'm telling this story about what I experienced, no matter who that person was that pulled me in that room, you have to understand that was an experience I went through that's really scary, and I felt really unsafe," she stated.

In the cease-and-desist letter obtained by People, Britney's attorney, Mathew Rosengart, asked Jamie Lynn to stop sharing stories about her sister's life with the public. "We write with some hesitation because the last thing Britney wants is to bring more attention to your ill-timed book and its misleading or outrageous claims about her," the letter starts. "Although Britney has not read and does not intend to read your book, she and millions of her fans were shocked to see how you have exploited her for monetary gain. She will not tolerate it, nor should she."

It continues, "You of all people know the abuse and wrongdoing Britney had to endure during the conservatorship, after initially growing up with a 'ruinous,' alcoholic father. In fact, your own book reportedly states that your father 'spent most of my life in that cycle of ruinous behavior. His bouts of drinking caused me periods of torment and sorrow.'"

The letter concludes with: "As I have previously stated, having endured a 13-year conservatorship that stripped her of civil rights and fundamental liberties, Britney will no longer be bullied by her father or anyone else . . . Britney was the family's breadwinner and she also otherwise supported you. Publicly airing false or fantastical grievances is wrong, especially when designed to sell books. It is also potentially unlawful and defamatory."

In a letter obtained by TMZ and Page Six, Jamie Lynn's attorney, Bryan J. Freedman, responded to the cease-and-desist letter from Britney's attorney, Mathew Rosengart. Freedman began by referencing Britney's latest Instagram post, in which she stated she should have "slapped [Jamie Lynn] and mamma right across your f*cking faces" and "whipped your ass," calling them "cyber bullying which cause death threats to Jamie Lynn and her family."

He continued, "It was also disappointing to see your Letter plastered all over the media, as it would have certainly benefited all of the people involved and their respective children, if there was a private forum to try and redress any grievances."

Freedman went on to claim that because Britney and her attorney have not read the book, the cease-and-desist "fails to specify any legal wrongdoing whatsoever." He later added that his client described Britney as "a kind, supportive, and a protective sister, whom Jamie Lynn looked to as a second mother."

"Your claim that Jamie Lynn has no right to tell her story is not only insensitive but not supported by the law. Jamie Lynn is a member of the Spears family. Your Letter ignores a critical fact: Jamie Lynn has suffered through her own experiences, and her own trauma. Had you taken the time to read the Book prior to sending your Letter, you would know that the Book is not about Britney, but instead about Jamie Lynn's own experiences growing up in the same family and describing what life for her was like as part of that family," Jamie Lynn's attorney stated.

Britney started off by apologizing to Jamie Lynn for previously calling her "scum" before calling her out for spreading lies about her. "It's like you're going out of your way to lie about me and make me look bad 💔 !!! And if I wasn't your sister I would believe everything you're saying in your interviews … you're actually believable !!! It's scary 😱 !!!" Britney wrote.

The singer then referenced a time when Jamie Lynn and their dad were allegedly poking at her broken foot, adding, "I felt ganged up on so I said 'shut the f*ck up !!!' I never stick up for myself, so you were shocked !!!" Britney also brought up how Jamie Lynn reportedly never let her hold "the baby." "You would just yank her out of my arms !!!! You acted like you owned that household and I'm sorry you were too much," Britney wrote. "I know dad has taken a back seat because he doesn't do the conservatorship anymore so I guess you're feeling that your little sassy ass can boss them around, but I'm here as your older sister to keep it real with you and put you in your place !!!"

She continued, "You have the right to tell your story but honestly the timing … right when people are just counting down the the seconds until I do something wrong, you come out and literally say hurtful things about me lying … that's being so unsupportive and it's kind of insane … I'm honestly wondering if this is all a joke and you're testing me because this is so far from you it's not even funny … 💔😔."