Kristen Stewart Cheats on Robert Pattinson With Director Rupert Sanders

Celebrity News July 24, 2012 AT 8:15PM By UsWeekly Staff

Robert Pattinson's biggest fear has been realized.

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 her Snow White and the Huntsman director, Rupert Sanders, 41 -- and the new issue of Us Weekly has the exclusive photos and details.

PHOTOS: Kristen Stewart and Robert Pattinson's undercover PDA

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.

VIDEO: Rob and Kristen in happier times

Reps for both Stewart and Sanders had no comment.

For more details on Stewart's affair -- from her initial interactions with Sanders to how her infidelity will affect her Twilight Saga: Breaking Dawn -- Part 2 promotional duties with Pattinson -- pick up the new issue of Us Weekly, out Friday!

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