Help me, please.

I don’t know what you’d call this. No idea, but me and my step dad have had a terrible relationship since I was 10. He is very clingy and will ignore me for weeks if I don’t give him hugs, cuddle or talk to him enough. He has once beaten the crap out of me for not wearing a bra and when cps was called (by my actual dad) I was sent to therapy and told everything was my fault. I’m not about to be 17 and this happens, he’s been watching me shower and get undressed everyday from under my door. For months this has been going on and I caught him just recently. He told me that he would leave my mother and his son and leave us broke if I told and I wouldn’t want any of that to happen. He is also forcing me to maintain this “good relationship” with him because if not he will leave. I feel like throwing up every time I see him and I just cry and hate myself when I can’t tell my mom why I don’t like him nor why I can’t maintain a relationship with him. I think he’s creepy and disgusting but when I told him, it was all blamed on me for not being normal and not being able to be nice or anything else he could find wrong about me. Ultimately I just wanted to tell someone, I can’t tell my boyfriend of 6 years because obviously and how would I look to my friends. Anyways, and advice or comments would help. Thank you.