This continues to be a tough moment for Britney Spears' relationship with sister Jamie Lynn Spears.
A source tells E! News exclusively that Britney feels "totally abandoned" by her younger sibling amid the 39-year-old "Womanizer" vocalist's ongoing conservatorship battle. This follows Jamie Lynn's announcement earlier this week that she will soon publish a memoir covering various aspects of her personal life.
"Britney is very, very angry and hurt," the insider shares. "She feels like Jamie Lynn totally abandoned her and let her down in the fight of her life. They were best friends and everything to each other for so long."
The source continues about Britney, "She asked for support, and feels like Jamie Lynn turned her back on her and couldn't be bothered."
E! News reached out to Jamie Lynn's rep for comment and has not heard back.
On Monday, Oct. 11, Jamie Lynn shared on Instagram that she has finished writing her book, Things I Should Have Said, which is scheduled for publication in January 2022.
"I felt a strong conviction to share my story, but there was a lot of personal work and healing that had to happen before I could share my truth the proper way," the 30-year-old Zooey 101 alum posted in part.
A day later, Britney appeared to subtly mock the announcement by writing on her own Instagram account, "Psssssss also great news … I'm thinking of releasing a book next year but I'm having issues coming up with a title so maybe my fans could help !!!! Option #1 … 'S--t, I really don't know' Option #2 … 'I really care what people think.'"
The "Stronger" singer has previously used social media to vent about perceived betrayal by those close to her. In July, Britney posted to Instagram, "There's nothing worse than when the people closest to you who never showed up for you post things in regard to your situation whatever it may be and speak righteously for support."
The next day, Britney wrote that she didn't "like that my sister showed up at an awards show and performed MY SONGS to remixes." This was an apparent reference to Jamie Lynn's tribute performance at the 2017 Radio Disney Music Awards.