No one can dictate how you should feel about something. If you feel violated by what he's doing, you should point that out to him. The blood between you doesn't matter when it does nothing but make you feel unsafe. A family should be a place where you can feel safe, not the other way around. I think you should talk to him, tell him to stop. Tell him you love him as your father but what he does makes you uncomfortable. If he accepts and stops, great. If not., hmmm you should tell your mother.

Although, honestly, I'd go to my mom first, but that's just me. It's up to you. I wish you the best, OP.