KRISTEN STEWART is reportedly cheating on ROBERT PATTINSON with her “Snow White and the Huntsman” director RUPERT SANDERS, according to the latest Hollywood news reports.

Say it ain’t so, K-Stew!

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While we’d all love to believe that Robert is the only man she’s kissing when she’s not on a movie set, her track record with relationships betrays her. After all, everyone knows that Kristen was still in a relationship with Michael Angarano when she started going out with Rob (a move which earned her a lot of hate mail from fans).

So is the “Snow White and the Huntsman” star cheating on her man with married director Rupert Sanders?

According to Us Weekly:

Kristen Stewart, 22, was caught in a series of steamy rendezvous with her Snow White and the Huntsman director, Rupert Sanders, 41.”

The celebrity gossip mag then goes on to claim that they actually have photos to prove the affair.

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One source, however, insists that it was just a one-time thing—not an ongoing affair. The insider tells PEOPLE:

“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.”

The source continues:

Kristen is absolutely devastated… It was a mistake and a complete lapse in judgment.”

Okay, Kristen. Tell that to the hordes of “Twilight” fans who will surely be monumentally pissed at you…

Do you believe that Kristen cheated on Rob?

Photos By PR Photos

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