You are amazing, girl. I know this is so hard. And eventually, maybe when its too late, he will completely regret this.

Don't let your dad get you down. You know who you married, you would never marry someone with bad character. Someone to be your lifetime spouse and possibly the father of your children. Your H changed, for whatever reason. If you have to, tell your father something like "I know this is hurting you too, but I know my H was a good man. He is lost now, and I have to move on. I realize that, but I would appreciate you not dragging our history through the mud"

HUGS!