I totally know what you are going through. The same thing happened to me and one of my friends. We were so close and know we barely talk except about school or home work.
You just have to sit down and talk to him before you two drift further apart. i wish i would of done that it may have saved our friendship. if you talk then maybe you two will be able to salvage some of your prior relationship.
i hate saying it, but with what happened you lost something as friends that will be exstremely hard to get back. If you talk it out, though, you will have a better chance of getting it back.
Let us know how everything turns out between you and your friend. Good Luck!