The ex-husband of pop star Britney Spears gives new details on the pair's tense relationship in his new memoir You Thought You Knew.
Kevin Federline, her one-time backing dancer, presents a picture of Spears's allegedly erratic behaviour as a wife and mother, and says he continues to have concerns for her wellbeing.
Spears has spoken out against the book, which will be published on Tuesday, and accuses Federline of trying to profit from his association with her.
The pair got together in the summer of 2004, after Spears's commercial peak.
They married a few months later and quickly welcomed their two sons: Preston, now 20, and Jayden, now 19.
Spears filed for divorce in 2006 and the divorce was finalised in 2007.
The couple fought publicly over custody of their sons and ultimately Federline was given sole custody of the boys.
In the wake of Federline getting full custody, Spears was seen behaving in a way that Federline characterises in his book as erratic.
She made headlines with incidents like shaving her head and hitting a photographer's car with an umbrella.
Those public incidents raised concern about her mental welfare, and after she was taken to hospital twice, a temporary conservatorship was established in 2008 and made permanent later that year.
Spears remained under that controversial arrangement until 2021, under which her father and others controlled her finances and aspects of her personal life. She did not regain custody of her children until after it was lifted.
While the pair dominated headlines during their relationship and subsequent divorce, Federline in particular has largely remained out of the limelight in recent years. And recently, the spotlight on Spears has largely been over her social media postings.
Federline has said he considered writing a book for many years but wanted to wait until his children were older to complete it.
"I picked it up and put it down quite a lot over probably a five-year period," he told the Associated Press. "I think that it's a very good description of me, who I am, the father I've become, the husband I am, the ex-husband I am."
He also told AP: "I want my children to be able to move forward in their lives and know that the actual truth of everything is out there."