The thing you must remember, is that as a girl... no, as a human being, it's your right to say "No" at any given time.
If he so much as breathes on you in a way you don't like, you have the right to say no, and don't ever let anyone tell you otherwise.
A female friend of mine was raped because she was just too afraid to say no or even scream. She couldn't get over the shock, and just cried horribly afterwards. Please don't let that happen to you. Just remember that it's perfectly fine to say no whenever you like.