The heartbroken actor has packed his bags and left the couple's residence after she confessed to cheating on him with director Rupert Sanders and he is now said to be in seclusion.
A source told People: ''I'm not sure they'll be able to recover from this. Robert is heartbroken and angry.''
After pictures emerged of Kristen and Rupert - who has two children with his wife Liberty Ross - kissing, the 22-year-old actress issued a statement saying how sorry she was.
Kristen - who started dating Robert after meeting on the set of the first 'Twilight' film -said: ''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.''
Kristen is now determined to win Robert back with the insider adding: ''Kristen really loves Rob more than anything. He's all that matters to her right now.''