Us Weekly first reported yesterday that Twilight star Kristen Stewart had cheated on co-star Robert Pattinson with Snow White and the Huntsman director Rupert Sanders. Sanders, 41, is married to Liberty Ross, 33, who he has two children with.

During a public makeout session between Sanders and Stewart, "it seemed like they couldn't get enough," according to one photographer who snapped pictures of the encounter.

Reps for both Stewart and Sanders had initially had no comment, but earlier today, Stewart released a statement saying:

"I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected. This momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect the most, Rob. I love him, I love him, I'm so sorry."

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!