Funny lady Jenny McCarthy is opening up about some of the darkest days in her life, when at age 2, her son, Evan, was struck with seizures, and withdrew emotionally and socially, until he was diagnosed with autism. 

"It brought me to my knees nightly, where I would have emotional breakdowns," she tells our Mark Steines. "The pain was so extraordinary it felt like I was going to die, or I had to check out for a little bit."

Jenny says she suspected that toxins such as mercury, aluminum, formaldehyde, MSG, or live viruses found in some traditional children's vaccines were causing the condition, but she was pooh-poohed by pediatricians.

"The heartbreaking thing is watching your baby get sick and, in Evan's case, he had cardiac arrest and died in front of me, and knowing what caused it and having no one believe you," she says.

Jenny wrote about the condition in her book, Louder Than Words: A Mother's Journey in Healing Autism, and says Evan has returned almost to normal thanks to dietary help she found through the autism research organization, Generation Rescue. This Saturday at 9 p.m. on NBC, she's joining WWE wrestler John Cena as a guest-star on the "Saturday Night Main Event" and hopes wrestling fans will help donate funds to Generation Rescue to help fund more research and help families struggling with the disease.

"When it happened to me in my home, I also got divorced in the same month," she says. "I had to double-mortgage my home to pay for autism."

She also credits boyfriend Jim Carrey with helping bring son Evan out of his shell: "I kept calling him the autism whisperer. He got Evan to not be afraid of the water and things like that."