I'm not going to let my girlfriends dad in our house
Why wouldn't you let your gf's dad in?
He hates me, he's an asshole.
It's your household, so you have all the say as to who lives in it. If having your girlfriend's dad in the home will wreak havoc, then he shouldn't stay there.
I want to make trouble for him. If he doesn't leave our house, I will have cops here for sure.
I don't think you'd have to go that far, but you should tell him that it's your house and he's not allowed in.