Robert Pattinson is reportedly "on a mission" to confront Rupert Sanders.

The devastated actor is said to be gearing up for a talk with the man who had an affair with his long-term girlfriend Kristen Stewart.

According to sources, the Twilight star has prepared a list of things he wants to tell the married Snow White and the Huntsman director.

"He is on a mission to confront Rupert straight up," a source told the US edition of OK! magazine. "Rob wants to look Rupert in the eye and say, You ruined my life.' He has all these speeches prepared in his head how Rupert's not a real man, and what kind of person not only cheats on their own wife but tries to steal another guy's girl?"

It has previously been reported that Robert wanted to speak to Rupert to find out exactly what went on between him and Kristen because he didn't trust his cheating girlfriend to tell the truth.

Meanwhile, the brunette beauty is said to be "petrified" about a potential meeting between the two men.

She is reportedly convinced her beau will never forgive her if he hears details about the alleged fling.

Robert has reportedly taken the news of the secret tryst badly and has remained out of the public eye since the scandal broke.

There are numerous reports that Robert is staying at Water for Elephants co-star and friend Reese Witherspoon's house in Ojai, California.