That's the whole game. By not talking to you, you have no idea how he is feeling. I'm sure he is hurt also. Maybe not as much as you as it probably isn't as important to him, but he is still hurting too. Shithead's right on this one. You won't be able to get him change no matter how hard you try or what you say. Classic mistake. My exgirlfriend tried the same and was so angry and pissed off at me at the end. I did just shut her out.
However, on the plus side, our breakup did help me become a new person with new priorities. I don't know if it's rare or not but I want to say that it's not impossible for him to turn a 180 after you keep him in no contact for a while. It took me a few months of educating myself, posting and reading on this forum, talking logic with a buddy of mine who is also working on an ex girlfriend, and so on to really right my ship. I had to really want to change and become a better person. I want to give him the benefit of the doubt here and say he could really change his ways and grow up a bit. He's going to have to want to on his own though. I'd hope so at his age, damn.
However, he dumped you. The tendancy in that is that he thinks he is right for doing so and looking for a reason to confirm that uncertainty. All the time you pine after him and talk to him and show him attention, good or negative, it's just solidifying his decision. He is stubborn and he won't budge. There isn't really much you can do or say. I know he's the only one that can make you feel better and you want the pain to go away but this is where the tough skin starts to form. Gotta toughen up and hold the no contact, even when he starts making the moves to you. It's gonna take some time. I understand you love him but put yourself above this relationship and realize that it takes both of your priorities lined up to make this work. You doin all the work is just a rowboat with one oar.