Toxic parent in laws..

I’ve been with my partner for 11 months this month, and always tried to make sure I get along with her parents but recently they’ve been slagging me off and being difficult… a week ago her dad told me that if I were to ever get a house with “HIS daughter” then I have to obey him, even if it means he is controlling.. then today he has accused me of lying even though I proved everything I said? It makes me so uncomfortable when I go over there and I feel it’s going to put a strain on my relationship with my girlfriend, but she can’t say anything to him because he will scream at her and make her life hell… what The hell do I do?!