I can't truly give advice as I separated once I found out my H had yet another affair.
But I can relate to the feelings of I hate you, I hate what you did to the kids, I hate what you did to me.
Who knows why they do what they do? If I was unhappy in my marriage I would go for some counseling or divorce, I wouldn't go out and cheat. That's only making everything worse.
I do hope his abusive tendencies are under control. For me, that would be a deal breaker.
Take care of you and your kids. Congratulations on the new addition
Edited to correct an error.