Robert Pattinson is finally free to see other men now, because his Twilight beard Kristen Stewart was busted on camera sucking face with the very married director of her “Ho White and the Cuntsman” “Snow White and the Huntsman” film. Us Magazine says:

On July 17 in L.A., the 26-year-old actor’s girlfriend and Twilight costar, Kristen Stewart, 22, was caught by photographers in a series of steamy rendezvous with director Rupert Sanders, 41.

Sanders — married to British Vogue model Liberty Ross, 33 — has two children, ages 7 and 5. During his marathon makeout session with Stewart, “it seemed like they couldn’t get enough,” according to one photographer.

Reps for both Stewart and Sanders had no comment.

Besides the photographic evidence (see below) and Rupert’s wife tweeting “wow” and then deleting her Twitter account, another source tells People magazine:

“Kristen is absolutely devastated… it was a mistake and a complete lapse in judgment.

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.”

This is usually the part where I write something snarky, but there’s nothing I could say that could possibly contend with the comedy gold that turns up when you search “robsten” on Tumblr. Such gems as “You think the Robsten breakup is hard? The Zanessa breakup, now that was hard” and “Robsten represented hope for me, hope that maybe, one day, I’ll find a boyfriend. Since I have no one to hug, I’ll just go hug my pillow” and the full lyrics to “Broken Strings” by James Morrison featuring Nelly Furtado. You can’t make this shit up.

Photos of the cheating + some of her with Pattinson and Taylor Lautner at the TCA’s on Sunday: