Kevin Federline has had a tangled romantic past, to say the least. And on the newest episode of 'Celebrity Fit Club' (Mon., 9PM ET on VH1), the ex-husband of Britney Spears confronts part of that past. Federline's former fiancee (and mother of two of his kids), Shar Jackson, is also a contestant on the show. And so K-Fed took time out from trying to lose weight in order to apologize to Jackson, whom he left for Ms. Spears.

Watch the video after the jump.Kevin Federline has had a tangled romantic past, to say the least. And on the newest episode of 'Celebrity Fit Club' (Mon., 9PM ET on VH1), the ex-husband of Britney Spears confronts part of that past. Federline's former fiancee (and mother of two of his kids), Shar Jackson, is also a contestant on the show. And so K-Fed took time out from trying to lose weight in order to apologize to Jackson, whom he left for Ms. Spears.

"I've been really selfish," Federline said to her. " I guess I got so wrapped up in all this other sh-t that I really never sat back and had a chance to apologize to you." Then he added: "I really do want you to know that I am sorry." Jackson seemed struck by the apology. "That meant the world to me," she said, her eyes clouding up with tears. "For the past few years, I was like I don't know who this dude is, like, inhabiting Kevin's body, but that's not him."