In a post on Twitter, Britney said that her younger sister was "never around me much 15 years ago," around the time her conservatorship was starting, adding, "So why are they even talking about that unless she wants to sell a book at my expense??? REALLY???"
Britney also accused Jamie Lynn of living off her success, adding, "She never had to work for anything. Everything was always given to her!!!!"
The 40-year-old pop star also claimed her family "ruined my dreams 100 billion percent and try to make me look like the crazy one."
Shortly after, Jamie Lynn took to Instagram, posting a statement regarding her sister.
"It's hard to see these posts, as I know the world also feels," Jamie Lynn wrote. "I just wish her well. Brit, I am always here, you know behind the scenes I have always been here. It's become exhausting when conversations, and texts we have in private don't match what you post on social media. I know you're going through a lot and I never want to diminish that, but I also can't diminish myself."
Jamie Lynn added that her family has received death threats, for which she blames Britney's "vague and accusatory posts," saying Britney could "tell the truth, and put an end to all of it in one second if she wanted to."
The mother of two added that she's remained silent in the past, but realizes that might not be possible moving forward.
"I may have to set the record straight myself in order to protect mine and my family's well being," she wrote. "That being said, 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 concluded the statement saying that although she's speaking her truth in order to move forward, "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 her Nightline interview, which first aired in part on Good Morning America, Jamie Lynn tearfully said, "That love is still there, 100 percent. I love my sister. 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."
"This book isn’t about me trying to clear up anything," she told ET. "It’s about me using my voice and showing my daughters that your voice is important -- that is what this book is about. But I hope that I guess what is happening in the recent climate, that people would understand that this is a situation that has affected many people. This is my reality that I've grown up in and it’s the only reality I know, and I’m allowed to speak about that."