Britney sent the letter amid the release of Jamie Lynn's memoir.
Jamie Lynn Spears is speaking out against Britney Spears' cease and desist letter. After Britney's attorney, Mathew S. Rosengart, sent a letter calling on Jamie Lynn to stop "referencing Britney derogatorily" in interviews and threatening further legal action if she refused, Jamie Lynn's lawyer, Bryan J. Freedman, responded with a letter of his own.
In Freedman's letter, which was obtained by ET, the lawyer calls Britney out for her most recent post about Jamie Lynn and their mom, Lynne Spears, which he called "vile."
"These include, but are not limited to, statements such as Britney should have 'slapped you and mamma right across your f**king faces!!!' and 'Whipped your a**,' and “popped the s**t out of your a**,'" the letter reads.
Freedman also claims that "Jamie Lynn has had her children violently threatened, and we have no doubt that these new intimidating and threatening social media posts will lead to similar threats of violence." Jamie Lynn has two daughters, Maddie, 13, and Ivey, 3.
Freedman's letter goes on to comment on how "disappointing" it is that the situation is playing out in public, rather in private, before addressing Jamie Lynn's book, Things I Should've Said.
In Britney's letter, which ET previously obtained, the singer's lawyer called Jamie Lynn's book and resulting press tour "potentially unlawful and defamatory," adding that the memoir, which neither Britney nor her lawyer has read, is "ill-timed" and contains "misleading or outrageous claims" about Britney.
"Your claim that Jamie Lynn has no right to tell her story is not only insensitive but not supported by the law," Freedman's letter reads. "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," the letter continues. "In fact, even where Britney is referenced in the Book, she is described as a kind, supportive, and a protective sister, whom Jamie Lynn looked to as a second mother."
Freedman's letter goes on to claim, "Jamie Lynn grew up in a family where she was constantly silenced and never allowed to have a voice. To send a Letter attempting to constrain her right and ability to speak the truth, only retraumatizes the very core wound that she has suffered from her entire life."
Freedman's letter additionally notes that "Jamie Lynn has wanted nothing more than to help her sister in any way that she can."
"Jamie Lynn hopes that there will be no further postings or inflammatory letters being sent to the media," the letter reads. "Beyond telling the truth, and denying the allegations against her, as a mother, Jamie Lynn needs to protect her children and cannot continue to be subjected to death threats, and other postings insinuating physical violence against her and her family."
The letter concludes, "Jamie Lynn supports Britney and as always, she hopes she can get the healing, peace, and freedom she rightfully deserves."
When ET spoke with Jamie Lynn, the Zoey 101 alum opened up about why she decided to write her book.
"I wrote this book so that I could show my daughters to use their voice," she told ET. "I hope that tells other people to do the same. Even if you’re afraid, and even if you feel like it’s something that’s scary for you to do, your voice matters. You should always feel like you can control your narrative."