Britney Spears has accused Jamie Lynn of spreading "lies" in her new memoir.
Earlier this week, the 30-year-old actress gave an interview to promote her new memoir 'Things I Should Have Said', in which she called out her older sibling for her "erratic" behaviour.
And the 40-year-old pop icon has responded in a lengthy statement and revealed she watched the interview while suffering from a really high fever.
Britney began on Twitter: "So I got really sick last night ... 104 fever maybe higher, not sure because I stopped checking !!!! I'm never sick so if I do get sick I'm a drama queen !!!! I needed Aleve for the pain in my head ... I had nothing ... I called my security 'can you please go get me something to relieve the pain in my head, my fever is pretty high...'
"Immediately 'Sorry, no. I can't leave the premises. I have to stay on property.' So I said 'Of course, unless there's an emergency and I have a 104 fever...' I told him the other security leave sometimes in emergencies... it wasn't what he said to me IT WAS THE SARCASM in his voice when he told me he couldn't go get it for me... oh well...
"Looked at my phone and I see that my sister did her interview to promote her book... I watched it with a 104 fever lol and It was actually kind of nice having a fever so high cause I had to surrender to not caring.
"Just couldn't give a f*** but my head hurt so bad... of course I'm a drama queen if I get sick so I think I was dying !!! I'm not even joking ... My body had chill bumps everywhere, like I was freezing yet my body was extremely hot and I couldn't move .... it was pretty intense. (sic)"
Britney then addressed the things the former “Zoey 101” star said that bothered her, including her "behaviour being out of control" and her sister remixing her songs.
Britney previously hit out at her sister when she performed a cover of her hit 'Till the World Ends' at an awards show in 2011.
The “Toxic” hitmaker fumed: "Anyways, the 2 things that did bother my that my sister said was how my behavior was out of control.
"She was never around me much 15 years ago at the time ... so why are they even talking about that unless she wants to sell a book at my expense ??? REALLY ???
“Then where the lady mentioned why did she accused you of doing remixes to 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 of remixes to go into a small venue show and on tours !!!! 13 years later they assign me as the MOTHER OF ALL ... (sic)"
The “Lucky” singer - whose father Jamie Spears was recently removed as Britney's conservator after 13 years - then accused her family of "ruining [her] dreams" and always handing everything on a plate to Jamie.
She wrote: "Britney sitting there seeing a 15 minute performance of everything I have ever wanted.... But see, I always was the bigger person.
“They all got to DO IT and PLAY ME and I always sat there and took it. But see, now it's a joke ... the last thing I would ever do is ask for what was just given to her !!! So yes, they did ruin my dreams."
Britney then announced she was taking a break from Instagram, as she fumed how "disgusted" she is with her family.
She concluded: "I won't be doing Instagram for a while. The media, this business has always been extremely hateful to me.
"I've given enough ... MORE than enough. I was never given back ever what I want.
"My family ruined my dreams 100 billion percent and try to make me look like the crazy one while I have a 104 fever, not being able to move in my bed !!!! My family loves to pull me down and hurt me always so I am disgusted with them !!!! (sic)"
During her interview, Jamie alleged Britney once "locked them in a room with a knife", and that she was "scared" on a number of occasions.