The ENQUIRER exclusively reveals the truth about Californication star David Duchovny's sex rehab - he cheated on wife Tea Leoni for years!

And it wasn't because of alleged online porn addiction it's because David was a very busy boy.

David entered rehab when Tea, his wife of eleven years, made the guilt ridden X-Files star confess to his compulsive tomcatting.

"He said Tea give him an ultimatum: Get treatment or our marriage is over," a source told The ENQUIRER.

The source also revealed that David repeatedly cheated on Tea during their marriage.  David is still very much in love with Tea but couldn't control his irresistible urges when he realized  he could sleep with any woman he wanted.

Tea became suspicious in recent months over David's moody behavior and starting questioning him, the insider revealed.

At first, David tried to lie him way out of the accusations but eventually was so overcome with guilt, he confessed his carnal exploits.

That's when their marriage exploded!

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