Devastation, anger, frustration and embarrassment. Within a week Robert Pattinson has learned he's been cheated on by Kristen Stewart, his girlfriend of four years, had her publicly apologize over her "momentary indiscretion" and moved out of the L.A. home they share. According to sources, Rob is in "total shock."

Earlier this week Us Weekly published photos that put Stewart, 22, in a compromising position with her married "Snow White and the Huntsman" director Rupert Sanders.  Since the photos went public, both Stewart and Sanders, 41, have released statements apologizing, and according to sources close to Pattinson, he is "horrified."

"As Rob told, me, 'She only had to call two people: me and Liberty [Ross, Sander's wife]," the source revealed.

"He is in total shock, but Rob is a very, very proud man," continued the insider. "And Kristen knew how he feels about remaining faithful, loyalty and commitment. He also was horrified that she issued a public apology to him."

While it was obvious that the "Twilight" co-stars have been dating since 2008, they have attempted to keep their relationship out of public light. Besides being snapped out together, the two rarely engaged in PDA. Their private relationship makes Stewart's statement of apology that much more dramatic.

Stewart's statement released on Wednesday read:

"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."

According to the source close to Pattinson, Stewart's apology was "unacceptable."

"It was even more surprising because the two of them had this very specific personal agreement about not 'going public' with their relationship, until they both agreed it was the right time," the source revealed. "To do it this way - apologizing for cheating on him - ended up being totally unacceptable."

Since news broke Robert Pattinson has moved out of the Los Angeles home he shares with Kristen Stewart. According to People magazine he has even cut off all contact with his cheating lover.

"I'm not sure they'll be able to recover from this," a source told the magazine.