Shauna Sands cheated on Lorenzo Lamas with his 18-year-old son

Lorenzo Lamas is no stranger to daytime drama, but even we couldn't make up the reason why he left former Playboy model wife Shauna Sands (his fourth, by the way). It seems mom was cheating on dad -- with then-18-year-old son A.J. Lamas! How Oedipal!

"Shauna came on to A.J.," a source told Star about the reason for the couple's 2002 divorce. "It was the ultimate betrayal. Lorenzo had no idea; he was in the dark about the whole thing."

Of course, this is all a carefully orchestrated media blitz to get you to watch the new reality show the Lamas family is shooting for E!, but still!

"He thought Shauna was acting like a mom to A.J.," the source added. "He had no clue that she was his son's lover!"

Thanks for taking all the drama out of it, Star. Now we don't have to watch, unless we want to know exactly how many months this whole sordid thing went on. Besides, our TiVo is too full of Denise Richards episodes to record it.

[Photo: Shauna and Lorenzo signing autographs in 2003 -- after the big divorce. How can he sit so close to her? Getty Images]