Amy Winehouse arrives at Pentonville Prison with her father Mitch to visit her husband Blake Fielder-Civil on December 11, 2007.
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In a new interview, Amy Winehouse's dad Mitch reveals that he cheated on his wife Janis and that the affair emotionally hurt his Grammy-winning daughter.

He says he began having an affair with a female colleague (who worked with him at a double glazing firm) shortly after Amy and her older brother, Alex, were born.

The affair was an open secret in the Winehouse home.

"The children used to call Jane 'Daddy's work wife,'" Mitch says on the upcoming BBC special, "One Life: Rock Star Parents," airing Tuesday.

When Amy was 10, Mitch left his family to move in with his mistress. The two later wed.

"It was difficult," he says. "I should have left earlier."

When he left, Mitch says, "there was not really a negative response from Amy, but she definitely became a lot more independent.

"Perhaps deep down she felt her parents were splitting up, she could not rely on them to stay together and that it was about time she learned to look after herself," he adds.

"I thought Amy was over it pretty quickly - in fact, it felt at the time Amy felt no effect at all."

But she suffered. Unable to articulate in words, she channeled her emotions in music.

In the lyrics to "What It Is About Men," Amy refers to the affair: "All the s--t my mother went through."

Mitch — who has since reconciled with his daughter — says he doesn't think his affair led to her drug and alcohol problems (which caused a seizure in August).

"I think she would have found her way here one way or another without any help from me," he explains.

"It is easy for me to say it is my fault, and that had I been a better parent, this would not have happened," he adds. "But who knows whether it would or not?"

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