Wow, your father sounds like a real piece of work. He sounds like he would be really rude to your girlfriend if he met her, so maybe it is just as well that he doesn't. I would keep telling him that he needs to stop saying such disgusting things about her and that you need your privacy.

Our parents do not always approve of our choices. Sometimes they have a reason, sometimes they don't. It's okay to make your own decisions without your parent's permission once you reach adulthood.