Oh man, you're in a similar mental state as I am. It seems to be cyclical, huh? I'm 1.5 months in and you're 2+ years in. I think that's the frustrating part. The pain doesn't dissipate and that's rather discouraging but please know that you're not alone. You're not at fault. You are worth more than this and you know that. There's no reason that I can tell that he can't be polite and cordial to you. Unless he's resentful that you seem to be able to and perhaps he sees that you're doing it easily (though you're probably not). Maybe he's acting mean because you seem to be doing just fine and are so polite. I'm not saying you should change that at all because there's great power in being kind in situations that are hard to be kind in BUT that see-saw occurs in almost every situation.
Keep being you. Be kind. Don't let his bitterness and unkindness chip away at you.
