Snow White and the Huntsman director Rupert Sanders believes that Kristen Stewart was the worst mistake of his life, according to friends close to the star.

Radar Online reports that the cheating director is desperately trying to save his marriage to model Liberty Ross after photographs of his affair with the Twilight actress emerged last month.

Rupert Sanders with his wife Liberty and their children

A source revealed that Sanders’ is fearful that his wife will file for divorce.

"Liberty is not making this easy for Rupert, not surprisingly.

"She is refusing to see him right now and has not spoken to him about if they have a future together or not.

"Rupert is willing to do absolutely anything and everything he can to save his marriage, he realizes this is the worst mistake of his life, and he cannot believe he was so stupid.

Rupert cheated on his wife with Twilight star Kristen Stewart

"The thought of losing his wife and children, who he loves more than anything in the world is killing him,” the source said.

Liberty Ross was spotted on Sunday with her children not wearing her wedding ring.

"Liberty has told Rupert she just doesn't think she will be able to trust him again," the source says.

"This affair went on right under her nose and she feels like he has made her look like a fool.

Robert Pattinson will appear on ABC's Good Morning America next week

"Rupert is just hoping it will blow over soon and he can win her back, but that is looking ever increasingly unlikely."

Meanwhile, it emerged today that Robert Pattinson will be making an appearance on Good Morning America on August 15.