Try not to feel so bad (I know that's easier said than done and you probably get tired of hearing that!!!), but overall it really wasn't the greatest marriage. He had affairs and left in the past. I just don't think you're losing anything that special. If he comes back a changed man that's one thing, but at this point he's really not worth someone special like you.
Hang in there buddy! You're going to make it.
There is no arriving, ever. It is all a continual becoming.