As long as he knows that you are there for him, there's really nothing you can do beyond that.
I agree with 20Wrongs' sentiment, in finding some good, healthy activities to fill your time. Simply waiting for these feelings to pass will only provide you with more pain, I think. Perhaps you can work on rebuilding yourself, and let these feelings pass on their own while you are doing so. Maybe you can try to accept these feelings, and feel these feelings, but at the same time don't let them rule your life.
Take care, and good luck.