Did Britney Spears “cheat” on Kevin Federline with a woman during their brief, ill-advised marriage?
One of Federline’s over-the-top claims in his new book claims that she did.
With the end of Spears’ child support, her ex-husband is clearly hoping that his memoir will sell well.
A salacious cheating allegation is a bold claim. What does Spears have to say about it?
You Thought You Knew is Kevin Federline’s memoir, out October 21 for anyone just dying to read his side of the story.
USA Today got a hold of an excerpt in advance, one that describes him allegedly catching Britney Spears cheating with a female dancer during a tour.
“Britney and I went to our room,” he says of the hotel in Amsterdam.
“But shortly after, she said she’d be right back,” Federline claims. “At first, I didn’t think much of it. The hotel floor was ours; they had booked it out for the entire tour, so everyone’s rooms were nearby.”
He continues: “But as time passed, I began to wonder what was taking so long.”
“Eventually, I decided to check if everything was okay,” Federline claims in the book.
Narrating in excruciating detail, he chews the scenery, writing: “I stepped into the hallway, our door still cracked, like most on the floor, and headed toward the elevators.”
He goes on to describe finding Spears: “As I passed one of the rooms, I glanced inside — and froze. There she was.”
According to Federline: Theresa was sitting on the edge of the bed. Britney stood between her legs, hands on her face, and they were (expletive) going at it. Full-on making out.”
He characterizes: “It was one of those moments that hits you so fast, your brain can’t even begin to process it. You just stand there, stunned, not sure what’s real.”
“I didn’t say a word,” Kevin Federline claims of allegedly catching Britney Spears kissing a woman. “Just stood there, watching. For a second, nobody moved.”
He narrates: “Then they both looked up and saw me, and I turned and walked away.”
According to Federline: “My heart was racing, but not with excitement. It was something colder, a sudden clarity.”
This alleged clarity was: “This wasn’t what I signed up for.”
“So I got the hell out of there,” Federline narrates. “As soon as I got back to our room, I grabbed my suitcase and started packing. At that point, I cared about nothing else — I just wanted out.”
Kevin Federline is breaking his silence about his explosive memoir, 'You Thought You Knew,' only on ET.
— Entertainment Tonight (@etnow) October 14, 2025
Sitting down with Kevin Frazier in Hawaii, Federline says he's speaking out now because he's concerned about what he calls Britney Spears' "erratic" behavior and the impact it… pic.twitter.com/pW5l3bQN0g
Unfortunately for Spears, their relationship did not end then and there.
In his book, Federline claims that she returned to the room to find him packing.
And then, for whatever reason, she allegedly begged him to stay — vowing that it would never happen again.
“I could tell she meant it. But I was still furious,” Federline writes in his memoir.
He explains his reaction: “I wasn’t interested in a relationship that involved more than two people.”
This was, apparently, when professional father Kevin Federline realized that he was “falling in love with Britney” Spears, he writes in the memoir.
Obviously, it is up to readers to determine if they believe him.
And, while not everyone considers kissing to be cheating, that is up for people within a relationship to determine.
Meanwhile, Spears’ reps told TMZ that “once again he and others are profiting off her and sadly it comes after child support has ended with Kevin.”
That same statement affirmed: “All she cares about are her kids, Sean Preston and Jayden James, and their well-being during this sensationalism.”