my boyfriend & his parents.

Okay. So, my boyfriend and I have been together for 2 years and his parents HATE ME. Like literally hate me. And try to keep him away from me. It clearly isn't working because we've been together for 2 years, but they hate me because of sex. I am 17 almost 18 and so is he, and they found out that we have a sex life and saw that we had sex in his bed and stuff and got really mad. ( in the beginning of our relationship ) and even 2 years later they still do everything in their power to keep him away from me, and he won't talk to them. What do i  do?