idealizing rape...

My boyfriend likes to I guess consensually "rape" me... he likes when I say no and try like fight him off of me durning sex. Eventually he'll either make me want it or tie me up. The first time we did this I was seriously not in the mood and it was hurting me but then I realized that he got more turned on the more I fought him. So I just kinda stopped fighting so we would get it over with. Afterwards I was kind of crying and he realized he hurt me and we had a conversation about like safe words and stuff but I'm not really into this whole fighting durning sex. I think he makes rape sound like it's a good thing and he kinda scares me when we're having sex... what should I do?