Simon Cowell is looking back at one of the toughest chapters in his life. On the Monday, June 10, episode of “The Diary of a CEO” podcast, the American Idol alum revealed the death of his parents took a serious toll on his mental health, but luckily, becoming a father brought him back to a better headspace. “I think particularly when I lost my mum, I was on a downward spiral at that point. I lost everyone, you know, I’ve lost my parents. It’s finality now,” the star, 64, explained. “Everything just meant nothing at that point.” Cowell said he was “desperately unhappy” and “wasn’t particularly …