Sanders, 41, who is married with two children, followed suit by apologising to his family, the People magazine reported.
"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," Stewart said in a statement.
News of Stewart's infidelity with Sanders became public only yesterday, four years after she met and fell in love with Pattinson on the set of 'Twilight', the vampire romance that made them famous.
The couple, who kept their romance under wraps despite a strong buzz, had started opening up about their love life only recently.
They were all laughs only two weeks ago at the Comic-Con awards.
Sanders said he was "utterly distraught" about the pain that he caused his family.
"My beautiful wife and heavenly children are all I have in this world. I love them with all my heart. I am praying that we can get through this together."
Ross
