In the U.S. you are right, there are statues of limitations on rape. Since it happened so long ago, it wouldn't get very far legally.
If I were you, I would not bring it up to him right now. If you did tell him that you believe he raped you, what is he going to say? He's not going to come over with a bouquet of white roses and describe eloquently how sorry he is. In fact what he might say to that is something that might be hard to hear/accept.
I think you should definitely talk to a therapist in depth. He/she might be able to help you work through this in your mind. There's more than one thing here that needs to be worked out. Like why, if you thought he raped you, did you feel like you should keep having sex with him? That's not at all meant to sound judgmental towards you. Your therapist might ask you similar questions to help understand you better.
I definitely feel as though you should talk this out with a professional that could help you to put this to rest in your mind either on your own, or confronting this guy..