Simon Cowell says he "let down" his friend by having an affair with Lauren Silverman.
The music mogul's girlfriend - who is pregnant with his son - was married to his friend Andrew when they got together, and while he feels guilty he admitted news of the baby helped got him out of a rut.
He told the Daily Mail Weekend magazine: "I let down a friend and I feel bad about that, but the good thing it is that I'm having a baby and I never thought I would.
"And it totally changed everything. It was like coming out of a fog; that's the only way I can describe it.
"I thought: 'Stop feeling sorry for yourself, you've got nothing to feel bad about'.
"It just makes you feel like you've got a responsibility. I definitely feel better. I thought I was going to freak out, but I didn't. It was only the circumstances that were problematic."
The 54-year-old star also revealed his mother is excited for the new arrival despite the affair, and he had to tell her before it reached the press.
He said: "She was actually very cool about it, but it was fairly traumatic when it happened and I had to call her before the story broke in the press but she was very calm and understanding."