09/20/2007 AT 04:00 PM EDT
In her emotional new memoir, Louder Than Words
, Jenny McCarthy documents life with her 5-year-old son Evan, who was first diagnosed three years with having autism. And in the latest PEOPLE cover story, she talks about his remarkable progress with the boy, thanks to some controversial therapies she found.
"I don't want to come across like a preacher," says McCarthy, 34. "All I'm doing is showing there are things you can do to ease autism." Of how Evan has advanced, she says, "At 3 he had the skills of a 1-year-old. [Now] people are shocked when they meet him."
While Evan's condition took a toll on her life, McCarthy's marriage to his father, John Asher, was brought "to an inevitable end," she says.
But now there's another man in her life: Jim Carrey, 45, whom McCarthy has been dating for more than a year in what she calls "a beautiful relationship – and I'm glad to say there are three of us in it."
At first, it took time to introduce her son to Carrey, she recalls, "But Jim reacted better than anyone ever did. He was intrigued. He asked questions. ... Beyond doubt it was written in the stars that Jim and Evan were a pair. He's actually helped Evan get past some obstacles I couldn't."
For more on Jenny and Evan's story, including an exclusive excerpt from her book, pick up this week's PEOPLE, on newsstands Friday Who's turning 40? Which celebs are high school dropouts? What's hot and definitely not in fall fashion? Check out PEOPLE's new digital magazine now!