While Pattinson is yet to comment publicly on the scandal, a source told The Sun he was “in shock” and had packed his bags.
The 26-year-old star was “heartbroken and angry”, the source added.
The Twilight stars shared a pad in LA and were the picture of the happy couple at the Teen Choice Awards on July 22.
But that has all come crashing down after 22-year-old Stewart was snapped in what looked like a romantic clinch with Snow White director Sanders, 41, who is married to Brit model Liberty Ross and has two children.
Both Stewart and Sanders have issued public apologies over the indiscretion, rumoured to have been a fling rather than a full-blown affair.
Stewart is said to be desperate to win Pattinson back.
She said in a statement: “This momentary indiscretion has jeopardised 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.”
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