Have you tried speaking with him about this? Maybe you two could work something out where you will both listen to each other, and try to support the other. In return, you will get support. He may just need you to sit down and ask him this. He may be so caught up in his own problems, he just isn't thinking clearly, and he isn't realizing the pain you are going through.
If he truly is unwilling to support you, then the best thing I can suggest is that you still try to be there for him, but you also try to find another support system. You'll need it in these trying times. Do you have any other close friends? Or could you even just call and talk to your parents? You deserve to have someone behind you. =)