Since splitting with Spears in 2006 – and then watching in fear as she went through her very public breakdown – the former backup dancer, 30, has channeled all of his energy into their sons Preston, 3, and Jayden, 2. (Federline also has two kids, Kori, 6, and Kaleb, 4, with ex-girlfriend Shar Jackson, 32.)
Now that Spears, 27, is getting her life back on track, they're sharing parenting duties again – and Federline is ready to tell his side of the story exclusively to PEOPLE.
Do you remember when you first met Britney?
I met her at a club in Hollywood, Joseph's. Our eyes met and that was it. We just hit it off right away. I learned real fast how much of a whirlwind the press and everything was.
What are your happiest memories of the marriage?
Well, getting married. I never thought that I would get married but it wound up happening. That was a really, really, happy, exciting moment. I pretty much realized that I was giving my life to her, and I was doing it without question.
What went wrong?
It's hard enough to be in a marriage, and then have a kid, then kids, it changes everything. For me, I'd become more concerned with my children. Not that I ignored Britney, but my kids are always most important ... I mean, we were having complications. I didn't give her an ultimatum, but I was trying to work stuff out with her, and she didn't even talk to me or anything and went behind my back and filed [for divorce]. [I was] completely blindsided.
A lot of people assumed you fought for custody of the kids because of money.
My first question to [my lawyer] was, "Am I ever going to be able to see my children?" I told him that I would spend every last dime that I had to make sure that my children are okay. That's all that mattered. I didn't know how much power Britney had. That really scared me.
How did you react in January when Britney locked herself in the bathroom with Jayden and was later taken to the hospital on a gurney?
That whole night is a blur. You want to talk about one of my lowest points of depression, that was probably one of them. I was very, very worried for her 'cause I care about her. That's the mother of my children. Just because I'm not in love with her doesn't mean that I don't love her. I'm definitely rooting for her. There's nothing more that I want than for her to be in the best health and doing what she loves to do.
Are things getting better?
Oh, man, it's totally turning around. It works out that [the kids] get to see her. There's structure over there, there's structure at my house. We're trying to keep the same type of schedule. It doesn't have to be completely perfect, but the foundation is there.
Dana Fineman / Contour by Getty Images
Where it all began: Brit falls for a backup dancer with a family!
2000: Brit's teen sex appeal sells 18 million records
See how Brit turned her year around!