Behind the laffs –two nasty divorces took their toll on ROBIN WILLIAMS.

Before finally finding happiness with third wife Susan in 2011, Robin Williams’ previous two marriages ended in nasty divorces. After an extramarital affair with a cocktail waitress in 1984,  she sued him, claiming he infected her with herpes.

In an ironic twist, it was revealed in court that that mistress – identified as Michelle Tish Carter – claimed that Robin threatened to kill himself by jumping out a hotel room window if she didn’t continue their two-year-relationship.

His second marriage to wife Marsha ended in a mess after 18 years of marriage in 2008. At the time, The ENQUIRER exclusively reported that Robin had been two-timing his wife Marsha with a woman half his age before she hit him with divorce papers.

Back then, The ENQUIRER revealed there was another women in the life of the Oscar- winning actor, a blonde from Greenwich, Conn. Sources said Robin, 56 at the time, met the divorcee through a pal and the woman’s friend.

Disclosed the source: “Robin has kept his relationship with her very quiet, and she obviously was keeping it a secret because up until just now he had still been married. “But the fact is, he’s told her that he and Marsha had been on the rocks for several years, and when he fell off the wagon and in 2006 and entered rehab, their marriage never really recovered.”

In January 2007, we reported that Marsha, showing him “tough love,” hadn’t allowed him to move back into their northern California home.

But he was traveling back and forth there to see their children and also to “date” his wife, which she was “permitting him” in an attempt to rebuild their relationship. Williams eventually returned home, but the couple divided their time between their San Francisco home and a lavish 244-acre estate in the Napa Valley wine country.

On March 21, 2008, Marsha, 58, filed divorce papers citing “irreconcilable differences.” But when he met graphic designer Susan three years later, the mistress was out of his life and he walked down the aisle for what would be the last time.