If you don't want to have sex tell him your not ready. If he can't accept that then break up and move on because he's a jerk.

If you don't know what you should do it means you aren't ready 

Honestly my suggestion is to wait. Unless you are ready for a lifetime commitment, you shouldn't have sex because of two reasons. First emotionally you will be "connected" after sex, that's just how humans are wired. Secondly if per chance you did get pregnant, sharing a child will connect you two for at least 18 years. Just my opinion, but waiting is healthier for you in the long run. P.S. I agree that if he's not willing to wait for you to be ready, then he's not worth your time :)Good luck with the decision