Always been homophobic, now afraid I might be gay

Ok Im going to be totally honest here and say that Ive always benn kind of homophobic. I never wanted to, like, beat up gay dudes or anything but I always figured being gay was kind of sick and pathetic. Ive called gay guys names behind their backs forever, mostly "f*****". Ive never even felt bad about it until now.

Anyway, I was always proud to be straight. Im 23 and have been with a few girls and only watched straight p*** and stuff. Sure I preferred the dudes to have big c**** but not because I wanted to look at their c**** or anything.

So I have an older brother who I always figured was as straight as me. Im staying with him for a few weeks over the summer and when I got there a couple of days ago I got there in the morning instead of afternoon when i was supposed to. I cant find him when i get there so I go upstairs to look. When I get there his bedroom door is open and I hear a lot of moaning. I sneak over and look in and I see my brother on the bed on his back with his feet up on some dark skinned dude's shoulders and the guy is f****** his ass hard.

Just looking at this guy from the back I can tell that hes lean and muscled and I realized I was staring at his clenching ass and jiggling b****. I got hard and almost came in my pants. All i could do was get out of there as quiet and fast as i can.

I ended up driving around the city for hours but my erection wouldnt go down. Twice I had to pull into a back alley and j*** off until I came. Im even touching my d*** as I write this in my brother's spare bedroom. When i close my eyes I can still see him getting f***** by that dude. I have no idea what to think or what to say to him.

The worst thing is that now Im thinking of my brother as a f***** and Im calling myself one inside my head too. I shouldnt but thats what im thinking. Does this mean Im gay?