SHOCKING: Kristin Stewart Cheated on Robert Pattinson With Married Director

US Weekly

US Weekly Has the Photos of the Twilight Star Making Out With Her Snow White Director

In the ranking of recent celebrity scandals, this one ranks right up there with the Katie Holmes/Tom Cruise divorce: US Weekly has photos of Kristen Stewart cheating on boyfriend and Twilight co-star Robert Pattinson with the director of her latest film, Snow White and the Huntsman.

Read: Kristen Stewart's Sexy "Thrusting" Nearly Got 'Breaking Dawn' an R Rating

The rendezvous between Stewart, 22, and director Rupert Sanders, 41, who's married with children, reportedly took place on July 17 in Los Angeles.

Photographers took a series of photos -- described as "steamy" by US Weekly -- that show Stewart and Sanders during a "marathon makeout session." One photo teased on the cover of the magazine's new issue shows Sanders with his arms wrapped around Stewart and kissing her.

Sanders is married to British Vogue model Liberty Ross, the mother of his children, ages 7 and 5.

Meanwhile, People.com is also reporting the news, including confirmation from a "source" that "Kristen is absolutely devastated. It was a mistake and a complete lapse in judgment."

Read: Robert Pattinson Cheating on Kristen Stewart?

The source, clearly a member of Team Stewart, also tells People.com, "She wasn't having an affair with Rupert. It was just a fleeting moment that shouldn't have happened. She never meant to hurt anyone. She's a good person who just made a bad choice."

Stewart and Pattinson, 26, have been dating since meeting on the set of the first Twilight movie in 2008, and seemed happily still together when they appeared at Comic Con just days before Stewart's makeout session with Sanders was caught by paparazzi.

Check out our slideshow of the couple in happier times:

More Photos »