The Jenny Craig spokesperson goes public for the first time about some of her lowest moments!

VALERIE BERTINELLI was America's sweetheart when she was the star of "One Day at a Time." But on Monday's OPRAH WINFREY show, she drops a few bombshells that reveal perception isn't reality. She discloses that she cheated on her husband and she snorted cocaine.

The interview airs the same day that Valerie's motivational book, Losing It: And Gaining My Life Back One Pound at a Time will be in stores. It is the story of her tumultuous 24-year marriage to rocker EDDIE VAN HALEN, her struggle to maintain a healthy self-image and more.

On tonight's ET, we have a sneak peek as Oprah asks, "So you got married?"

And Valerie responds, "And passed out in the honeymoon suite."

Valerie also tells the talk show queen: "I cheated, too. He claims to this day that I cheated first, but I don't know. I don't know about the timing."

But these days things are better between the now-divorced couple. Valerie told our CHERYL WOODCOCK in a 2005 interview, "We don't hold grudges about past mistakes. And we are there for our son period."

The new Jenny Craig spokesperson explains her reason for coming clean: "I just figured that if they are going to watch me lose 40 pounds and I'm going to be embarrassed that way -- and there's going to be fat-ass pictures of me with my butt hanging out in Hawaii, I thought, 'Why not let the inner me out, too?' 'Cause the inner me is, I hope, prettier than the outer me."

For more on this story, tune in to tonight's ET!