I know this is hard on you, most of us in here has probably experienced the same if not worse.
Aside from the fact that you're being hurt by his ignorance try and put yourself in his shoes. Not sure if it's your first time coming out (congratulations on that part) but there's a big chance you're the first to come out to him and so he wouldn't know how to respond to that.
There's also a high probability that he never socialized with people that are gay. So if this is all correct, you can't blame his ignorance. If you never played a game but you often hear about it, that doesn't mean you will be able to play it perfectly the first time you're holding a controller..
Give him a chance to process what just happened, he's probably trying to think about all those times you guys were together and how he didn't see this coming, when you get a chance just stay calm and explain to him why you're his friend and why he is yours and make it clear that he doesn't have to worry about you hitting on him. Tell him (jokingly) you can do better... Or something like that.
Outing yourself to a guy is much more difficult then a girl unless that girl happens to be in love with you for 5 years (which was in my case) *-shivers-*
I hope things will sort out for you quickly, wish you much luck!