Good luck with your dad - you're really a caring son and your parents should both be very proud of you!  I'm glad your father isn't physically abusive to you - sometimes when people have suffered from it as children, they turn around and repeat the same thing with their families (which is what my dad did), so he apparently is aware enough of that dynamic.  It would be nice if your mother could see a therapist, too, so she can feel better about herself and not take the hurtful things he says personally.  I hope everything goes well for them; I'd be interested to know how things turn out for your family.