The other thing to remember, too, is that you don't need to cut off contact forever. It might turn out that way, if he doesn't change and you decide you like the peace that comes with not having constant drama, but you don't have to make that decision from the start.
It's OK to tell your dad that you love him, but that for your own peace of mind you are not going to be accepting calls or other communication from him for a while. If he asks how long, you can say that you don't know but that your interactions with him are bad for you right now.
So it doesn't have to be vicious or mean on your part--how HE handles it is up to him.
Just something for you to think about.