From 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," Stewart said in a statement Wednesday.
Update: People just released a statement from Rupert Sanders, the director she cheated with.
"I am utterly distraught about the pain I have caused my family," Sanders tells PEOPLE in an exclusive statement. "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.