"You Thought You Knew" by Kevin Federline is out Oct. 21.

Britney Spears’ ex husband Kevin Federline is ready to share his side of the story.

“You Thought You Knew” (out Oct. 21 from audio-first publisher Listenin) details the start and end of Spears and Federline’s three-year marriage, including their divorce and custody battle over their two children. In an exclusive excerpt published by USA TODAY, Federline revealed a rocky and “whirlwind” start to their relationship, including Spears’ alleged cheating and “suffocating” fame.

In a statement to USA TODAY, representatives for Spears said: “With news from Kevin’s book breaking, once again he and others are profiting off her and sadly it comes after child support has ended with Kevin. All she cares about are her kids, Sean Preston and Jayden James, and their well-being during this sensationalism. She detailed her journey in her memoir.”

Federline’s memoir comes just two years after Spears’ “The Woman in Me” and fans’ fight to end her conservatorship with the #FreeBritney movement. He says his memoir is an attempt to “sound the alarm” on Spears’ behavior with their sons Jayden, 19, and Preston, 20.

“I see my sons trying to navigate this situation that's been absolutely difficult, and they're so young to even have to try and navigate a situation like this that I felt the need to sound the alarm,” Federline tells USA TODAY. “I need people to support my sons. I need people to support Britney. I need people to wake up and really look at this for what it is ... For two decades I feel like everybody else has told my story, and now it's time for me to tell it."

Kevin Federline says #FreeBritney movement 'got it wrong' and led to ‘conspiracy theories’

Federline writes he saw “history repeating itself” after Spears’ conservatorship ended, referencing social media videos of her dancing with knives. Federline said he felt “terrified, shocked, worried” for his children when he saw those videos.

He insists the “Free Britney movement got it wrong,” he writes, with their sons stuck in the middle feeling “powerless.”

Public outcry against the conservatorship reached a fever pitch after the New York Times' documentary "Framing Britney Spears" and Spears' emotional testimony at a 2021 court hearing, in which she called her conservatorship "abusive" and pleaded for it to end without undergoing another psychological evaluation.

“I think the ‘Free Britney’ movement started from a good place,” Federline says. “Everybody's kept quiet about this, especially me, because I was doing what I needed to do as a father, trying to raise my kids outside of this whole spectacle that's been put on us. That said, I think that just gave room for speculation, that gave room for conspiracy theories, that gave room for a huge movement to start.”

Kevin Federline revisits Britney Spears' 2008 involuntary psychiatric hold, bitter custody battle

Federline says “the beginning of the end” of their relationship was his 2006 Halloween album release night, where he writes that Spears did cocaine six weeks postpartum.

“Are you seriously going to go home after this and feed (the kids) like you don’t have a body full of drugs?” Federline writes. “I had seen it before, her drinking and breastfeeding, and it was really upsetting because of the danger to the kids.”

Federline says that memory was “one of the tougher ones to relive” in writing his memoir.

“You ponder over if things could have went different or if you handled the situation the right way, all of those types of things,” Federline says. “But at the end of the day, like I said before, everything's always been about my children. So I did what I felt was necessary for the sake of my family.”

Later, he writes he called his lawyer and told him about her “erratic behavior” and breastfeeding. She left voicemails apologizing. Then he found out just before a broadcast interview that she had filed for divorce.

Federline’s perspective of the aftermath includes Spears partying and calling drunk in the middle of the night with their sons crying in the background. Federline says that he also “started going out more, drinking more, slipping up and doing coke now and then” amid the custody battle.

Federline also writes about the much publicized 2008 incident where Spears locked herself in the bathroom with Jayden and refused to let him go, saying he was being abused at Federline’s house (Federline writes that it was eczema and allergies she was seeing, not abuse). The police were called, Spears was strapped to a gurney and rolled out of her home as photographers and helicopters swarmed. Spears was placed in an involuntary psychiatric hold, and Federline writes that was the “tipping point” that led him being granted sole legal custody of their sons.

Britney Spears allegedly held knife at sons' doorway

Federline writes their sons were the ones who decided not to go back to Spears' house, having recorded several incidents of her yelling, "berating" them and favoriting Jayden over Preston. He also alleges that Jayden and Preston would wake up at night to find her "standing silently in the doorway, watching them sleep" with a knife in her hand and then turn around "without explanation." Other nights, they'd wake to her screaming or "smashing things in the house."

Spears’ relationship with sons Preston and Jayden is “an ongoing fluid situation,” Federline says. Spears and her youngest son Jayden reunited in November 2024, USA TODAY reported, who said he believed his relationship with his mom can be fixed with "a lot of time and effort."

The infamous night Britney Spears shaved her head

Federline writes that Spears showed up to his house after she checked herself out of rehab, ringing the doorbell and shouting to be let in with a “swarm of paparazzi on her tail” and trying to climb the front gate. He wouldn’t let her see the kids because he “didn’t want to scare them,” he writes. Later, the photos of Spears shaving her head with electric clippers and attacking a photographer’s car with an umbrella emerged.

“That was the exact energy she brought to my gate earlier. Seeing those photos later, I thought: This is what I was dealing with,” Federline writes.

In “The Woman in Me,” Spears wrote that she was “out of my mind with grief” following the death of her aunt and the custody battle over her children at the time: "I am willing to admit that in the throes of severe postpartum depression, abandonment by my husband, the torture of being separated from my two babies, the death of my adored aunt Sandra, and the constant drumbeat of pressure from paparazzi, I’d begin to think in some ways like a child," she wrote.

Contributing: Charles Trepany

This article originally appeared on USA TODAY: Kevin Federline says #FreeBritney 'got it wrong,' plus more Britney Spears bombshells

Reporting by Clare Mulroy and Ralphie Aversa, USA TODAY / USA TODAY

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