
Sara Leal, 22, claimed she romped with the star in his hotel suite on his sixth wedding anniversary last month.
She claims Ashton, 33, wanted a threesome with her and best pal Marta Borzuchowski and both shared steamy kisses with the actor during the boozy party.
But she said he ended up just bedding her after Marta left.
They frolicked naked in the hot tub of his suite in the Hard Rock Hotel, San Diego, California, before having a two-hour sex session.
Sara claims Ashton told her he was already separated from wife Demi, 48, who was 2,500 miles away in New York.