What do I do?

Under 18? Still in high school then. Did you break up w/him? Were you his first real Girlfriend? If that is the case then there will always be feelings toward you but for him to get past the relationship mode of thinking it will take time. I myself had a girl that I went out with for 2 years up to my senior year in high school. She ended up cheating on me and breaking up with me after she told me. I tried the friend thing but I just couldn't handle it with out feeling an emotional attachment to her. Well go forward a couple of years and yes now I can talk to her. We aren't close but we still contact each other from time to time. You may want to lay low for awhile but don't take it personally because you probably had a significant impact on his life and he is now trying to cope with it.

By the way, if you were the one who broke up with him it does impact the male ego.

Maybe he feels that it will strengthen your two if you go back to being friends and then try to see if you still have feelings left for each other later? Or maybe he's an ass who is way too confused to makeup his mind lol. Maybe he needs time for him to decide what HE wants, but I don't really know. Boys are too complicated.