Just two years after Britney Spears' memoir "The Woman in Me," her ex husband Kevin Federline is putting his own pen to paper.

"For two decades I feel like everybody else has told my story, and now it's time for me to tell it," Federline told USA TODAY in an interview. "You Thought You Knew," out Oct. 21 from audio-first publishing company Listenin, delves into Federline and Spears' three-year marriage, divorce and custody battle over their two children. Federline also writes about Spears' drug and alcohol use and alleges his kids were afraid to stay at her house because she'd stand in front of their doorways while they slept holding a knife.

"Things happened the way they did, and I feel like staying silent was needed for my family and so that's what I did," Federline says, explaining why he chose to "sound the alarm" now. "Going back to the point of the 'Free Britney' (movement), I feel like staying silent kind of created a lot of the momentum for that because the truth wasn't out there, not the whole truth."

In the excerpt below, shared exclusively with USA TODAY, Federline shares a rocky start to his relationship with Spears while in Amsterdam for her tour. After a "whirlwind" start to their relationship, Federline writes that Spears told her tour team she wouldn't go to Europe without him. While there, he says he found her kissing one of her female dancers.

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.”

Exclusive excerpt from Kevin Federline's 'You Thought You Knew'

It was supposed to be unforgettable – iconic city, vibrant nightlife, and the kind of freedom you can’t find anywhere else. But for me, it became unforgettable for other reasons. The night started out simple enough. We all went out: me, Britney, and some of the dancers and staff from the tour, including Theresa, the girl who introduced us at Joseph’s. It was one of those loose, carefree evenings where everyone was dancing, drinking, and just having a good time. We stayed out late, hitting one of the city’s nightclubs until at least one or two in the morning. It felt like just another fun time on tour – a night you laugh about later. When we got back to the hotel, the group piled out of the SUV and headed inside. Britney and I went to our room, but shortly after, she said she’d be right back. 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. But as time passed, I began to wonder what was taking so long. I was thinking maybe she was catching up with someone or handling something tour-related.

Eventually, I decided to check if everything was okay. I stepped into the hallway, our door still cracked, like most on the floor, and headed toward the elevators. As I passed one of the rooms, I glanced inside – and froze. There she was. 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. 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. Just stood there, watching. For a second, nobody moved. Then they both looked up and saw me, and I turned and walked away. My heart was racing, but not with excitement. It was something colder, a sudden clarity. This wasn’t what I signed up for. So I got the hell out of there. 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.

I picked up the phone, called Fee, and asked her to book me the first flight back to the States. I didn’t care what time it was. I was ready to sit at the airport all night if necessary. I was done. As I finished packing, Britney came back into the room. She knew immediately, just by looking at me, that something was wrong. “What’s going on?” she demanded, her voice laced with panic. “I’m leaving,” I told her, my tone cold and final. “You can do whatever you want, but this isn’t what I came here for. If this is how it’s gonna be, I’m out.” In an instant, her expression shifted from confusion to regret. She started apologizing, explaining, promising it would never happen again. She told me she didn’t realize how serious I was about us, that she was overwhelmed, and it had been a mistake. For a moment, I saw her vulnerability. She was desperate for me to stay. Begging me. I could tell she meant it. But I was still furious. Still hurt. I told her that I wasn’t there for the “extra (expletive),” as I called it.

I wasn’t interested in a relationship that involved more than two people. I wasn’t judging her. I was simply laying down boundaries. I wasn’t going to let this set the tone for whatever we were building. Not to mention that Theresa was Marty’s ex-girlfriend.

I didn’t think about it then, but that moment was a turning point for both of us. It was our first fight, or whatever you want to call it. I think it was the moment she realized I wasn’t there for the fame or the perks. I was only there for her. The fact that I was ready to walk away, even after everything I had already given up to be with her, proved it was real. In the days that followed, something seemed to change between us. She became more intentional, more thoughtful about how we were together. It felt like we were truly starting to figure out what we meant to each other. Still, there were lingering doubts. I couldn’t shake the nagging voice in my head that wondered if I had made the right choice. I was thousands of miles away from my daughter. And the life I had stepped into wasn’t just fast-paced – it was relentless.

Every city brought new challenges. New eyes watching us, waiting for us to falter. Her fame wasn’t just hers anymore; it enveloped me too – and at times, it was suffocating.

There were also flashes of intense joy. I remember one afternoon in Sweden, sneaking away to a park near the hotel. We lay in the grass, made out, and talked about everything and nothing. Of course, photos of that afternoon surfaced later; but for those few hours, it was just us. Small, seemingly insignificant times like that became the foundation of our connection. They reminded me why I was there, making the madness seem suddenly manageable. More than anything, that tour opened my eyes to her world. I saw firsthand the pressures she faced, the endless demands of the industry, the constant scrutiny. When she had a few glasses of wine, she would open up and vent her frustrations – with the industry, with her team, with the weight of her fame. It was eye-opening, and honestly a little intimidating, to hear just how much she carried every day. Trust didn’t come easily to her, and I wanted to be someone she could rely on.

Those weeks in Europe, navigating that emotional minefield together, laid the foundation of our relationship. They tested us, changed us, and ultimately brought us closer together. It was during this time that I began to realize the depth of my feelings. And while the road ahead was anything but certain, I knew one thing for sure: I was falling in love with Britney.

Contributing: Ralphie Aversa

This article originally appeared on USA TODAY: Kevin Federline alleges Britney Spears cheated with female dancer (Exclusive)

Reporting by Clare Mulroy, USA TODAY / USA TODAY

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