Robert Pattinson has been distraught over recent news about his girlfriend of three years, Kristen Stewart's, cheating on him with "Snow White and the Huntsman" director Rupert Sanders, a father of two.

US Weekly reported that the "Twilight" star, 26, has been staying in Reese Witherspoon's $7 million ranch in Ojai, California.  Immediately after learning of the cheating scandal, Pattinson called his friend and "Water for Elephants" co-star if he could crash at her tranquil estate. Witherspoon, 36, wed husband Jim Toth in March 2011 at the ranch.

According to another source, Pattinson is "a total mess . . . He's questioning everything."

An "inconsolable" Stewart, meanwhile, has been reaching out via texts and phone calls.  "She's dying to save the relationship. It's the only thing she cares about," a Stewart source says.

Indeed, Pattinson, who fell for his "Twilight" costar nearly five years ago, "doesn't know what to do," said a concerned friend.

The story broke out on July 24 when US Weekly printed photographs of Stewart and Sanders canoodling on July 17.

According to People Magazine, Pattinson was utterly blindsided by the news.

"There was no sign that either of them was unhappy," says a source close to the 26-year-old actor. "He would have done anything for her."

While the source says Pattinson has had his "heart ripped out," a Stewart insider says the "Twilight" heroine, 22, is likewise devastated.

"Telling Robert was the worst thing she's ever had to do," says the insider.

According to Entertainment Wise via Yahoo, Liberty Ross, Sander's wife, forgave her husband of almost a decade for the fling. Pattinson, however, is said to be unsure about taking Stewart back and may approach the model to find out exactly what happened.

"He needs to know for his own peace of mind if theirs was just a fleeting moment," a source told Us Weekly.

"He hopes Liberty can help him find the answers he so desperately craves."

"Nothing is very clear at the moment but perhaps a meeting would lend some clarity to the situation. He needs to know the truth," they added.

Kristen Stewart issued a public statement through People, "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."

But a source claimed it went a lot further than that, telling Us Weekly: "She was caught up in a forbidden relationship with a man who should have known better.

"Somehow things got totally out of control. Kristen had wanted to end their closeness that day, but her desires and emotions got the better of her.

"She was caught up in the moment and totally besotted by him."

They went on to claim that she had no intention of leaving Rob: "She knew she did wrong, but realized how those photos would rip out Rob's heart. She has been in floods of tears since."

Radar Online reported that the "Twilight" couple is having a bitter custody battle of the dog they share.

On the pet front, Stewart will keep her cat, Max, but Pattinson wants Bear - the mixed mutt rescue they adopted from a high-kill shelter in New Orleans.

Stewart won't give up Bear without a fight; she's especially fond of the dog after helping him fight the potentially fatal disease Parvo.

"After Rob moved his things out of their Los Angeles home, he then told Kristen he wanted Bear," an insider said.

Despite the heartbreak and humiliation, the two must attend the November premiere of "Breaking Dawn Part 2."

The Sun reported:

They are contractually obliged to be snapped side by side on the red carpet.

A source said: "RPatz is in pieces but the Twilight love triangle storyline is nothing without him and Kristen. It is eating him up that he has no choice but to see her again because of work. His humiliation is total."

Marie Claire reported that "Twilight" promotional duties for Stewart and Pattinson start in October, and, according to insiders, Pattinson is 'dreading' having to hit the road on the grueling tour with Stewart, which will involve endless TV and red carpet interviews, not to mention posing together in photos.

Insiders close to Summit Entertainment said that the movie company is having a meltdown.

"This is a potential nightmare for all involved," the source said. "Fans look forward to seeing them together during interviews. It's great publicity for the film."