SS,

Have you bought any of Michele's books yet? If not, do so now. It sounds like your backing off is already having an effect so keep it up. Now about your moving out.... why do you have to be the one to move out? If he doesn't want to live with you that's his decision but he should be the one to leave not you. Keep validating everything he's feeling (I call this eating crow, swallowing bile, and then listening and understanding where they are coming from). If he says your marriage has always been horrible, tell him you understand how he feels and understand why he's saying that- even if you don't yet.
This will get better for you but it takes a long time. I'm not there yet.