I dont want to have sex with my boyfriend, but its getting to that point?

Okay, first off-just because you're 17 doesn't mean it won't last beyond high school. Another thing, if you cheated on him, then he has the right to know with who. So tell him that you need to talk to him about something very serious because he deserves to know and you want to be honest. Just tell him everything, who you did it with and what all happened. You shouldn't have sex with someone just because you feel like you owe it to them, sex should be saved for when you really love someone. If the person you're with cares about you they'll understand. If someone ever tries to force you into it or pressure you, leave them because they're not worth it and there's lots of nice guys out there who will want more than just sex. I'm not going to lie, your boyfriend could end up breaking up with you and if he does, you'll have to respect why he did it. Oh, and if you feel like things are heating up too fast, let the person you're with know that and tell them you want to slow it down or that you're okay with certain things but don't want it to lead to sex because you want to wait for that. So just let your boyfriend know, okay? I know it'll be hard and scary for you but he deserves to know the truth, it's the right thing to do. If he did something like that to you, you'd most likely want to know about it. Cheating is a horrible thing, don't do it again-learn from your mistake.