I am in love with my best friend, but I don't know if he's gay. What do I do?

I believe you should tell him how you feel. Shoot him an email or a message on facebook and be honest with your feelings towards him. I can honestly say If I had a very close guy best friend like this, I would hate to be able not to see him and keep in contact with him. Because of the fact that it would defiantly hurt me inside emotionally. You are one blessed lucky guy. Don't lose him Bro. Go get him!