I'm glad you're going into therapy too, although I have to agree with Perna.
Any man who has broken your self esteem to the point that he looks at you like an "old dog" instead of the loving woman who USED to trust him and love him, isn't some guy that I"D want hanging around MY bedroom! They say that once a cheater, always a cheater, and I tend to agree with 'them.' It's so easy to do and even if they get caught, the majority of them don't get much 'done' to them. So why shouldn't they keep it up?
He's got a lot of work to do in rebuilding your trust, plus helping YOU to build up your self-esteem that HE broke down. But that's only if you're going to keep him around.
You've got your own work to do. I hope you go to individual therapy and find out how you let this happen. Sometimes it happens so gradually, we don't even know it's going on. But emotional and mental abuse happens in marriages, and it can be so subtle that we don't have a clue. Then an affair goes on, and we get blind-sided.
Make sure you get some therapy too, okay? I don't know if you can "forgive" this or not. I'm not sure if I could, without bringing it up again during future fights, which isn't kosher. I think I'd be tempted to throw him to the curb. He doesn't deserve you. But alot depends on if you have kids too. They're the one who get hurt if you divorce.

God bless and please take care. Let us know what happens, will you? Hugs, Lee