Britney and Jamie Lynn Spears
She continued: "I hated that, like, that's not what you're supposed to do. You're 12," before saying her parents, Lynne and Jamie Spears, told her she "shouldn't be upset" and shouldn't "upset Britney."
"I said, 'You just saw me and my children be upset. When will I matter?'" Jamie Lynn added.
It's the latest family fallout between the sisters following the court's decision to free the Toxic singer from her conservatorship after nearly 13 years.
On Thursday, Britney released a lengthy statement in which she touched on her sister's latest book release.
She said there were two things from the interview which stood out to her.
Taking to Twitter, Britney said: "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???"
Jamie Lynn has been promoting her latest book
She added: "Then where the lady mentioned why did she accuse you of doing remixes of her songs… 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 never had to work for anything. Everything was always given to her!!!! If you were me, you might understand asking for 13 years for remixes to go into a small venue show and on tours!!!!."
She concluded by wishing her sister well with her book before confessing she won't be using Instagram again for a while.