Though it's no secret that his girlfriend was still married when they first began dating, Cowell hasn't addressed the affair in detail until now. Speaking to The Mirror, the first-time father says that "in a weird way," he "probably needed" to take a step back, clear his schedule and start a family of his own.
"You can start to live a slightly abnormal life and there is no question of doubt I was heading down that path," the X Factor creator explains. "Too many late-night phone calls. Too obsessed with things."
Cowell does "regret" betraying his friend, Andrew Silverman, when he started seeing Lauren. "But then of course you have a baby and you look at the baby and you kinda go, 'This is what happened from it.' In this situation you are not going to come out of this well because of the circumstances."
The 54-year-old, who welcomed son Eric on Valentine's Day, continues: "It is not something I am proud of or wanted to happen in terms of hurting anyone. It just happened. You have to deal with it and man up to it. You have to accept the responsibility and the criticism. All I can say is, my advice to you is if it happens to you, you just have to deal with it a day at a time and own up to your responsibilities."
Lauren, who has a 7-year-old son from her marriage to Andrew, got officially divorced in December.
"The great thing about Lauren is she loves what I do, so she sits in if I am watching Britain's Got Talent for example, and she has got a good opinion," Cowell says. "And I seem to have got my mojo back again."
Since becoming a parent, Cowell says he has become "more focused" on balancing his life and career than he was a year ago. "Maybe because it puts things in perspective having two people in my life who I am responsible for. There were times last year when I would live in two rooms, y'know kitchen and bedroom, in your house. It is a weird existence when you live on your own," he says. "On the phone all night, blah blah blah. Now the house is full of people. It has become a home rather than a house."
Cowell even stays up late to feed his son. "There is something about the noise of people around you that maybe triggers something back to when you were a kid in my house. That is probably what I am going through and why I am embracing it so easily," he says. "Eric doesn't cry much—he's as good as gold."
"He's beginning to recognize my voice and things like that," the music mogul adds.
Is fatherhood everything he imagined it would be? "Everyone said, 'It must be turning your life upside down,' but I love it. The dogs are mad and Lauren is not exactly the most quiet person in the world."
No one was more surprised than Cowell's own mother Lauren got pregnant. "She never thought at my age I would be turning up at Brighton with a grandson called Eric. She would never have predicted it."
"We were teasing people about the name being Simon," says Cowell, who chose his father's name for his baby boy. "Eric seemed the more obvious choice. Even though Lauren had never met my dad she knew my relationship with him was very strong and she felt quite passionately that he should be named after my dad. I thought that was sweet. We told my mum before anyone else."
Does Cowell want more kids? "I wouldn't rule anything out," he says coyly. "From here on in I am not predicting anything. The important thing this year is we have fun with what we are doing."
What about a wedding? "Wait and see," he teases.