"My [best] friend is gay" is probably what some guys type into Google after their friend tells them they aren't hetero. The results that come up are not particularly helpful.
And I obviously can't speak for all non heteros, but…
RE: I like dudesDear Hetero Bro,
If you're reading this then you know that your friend is not into girls, i.e. he likes guys. You obviously didn't get to talk about it in full because you're still thinking about it and looking for answers online.
Maybe he didn't tell you. Maybe you saw a picture, or an email, or a text or even something in real life. You're probably feeling freaked out/confused/angry/curious. Don't be freaked out. You might feel a bit like "you don't know him," but you do know him. This is your friend we're talking about. You just didn't know everything about him. He doesn't know everything about you either.
You also might be wondering if he's into you. There's no reason to assume he's attracted to you, unless you have another reason to think otherwise, like he told you or has hit on you. In the same way that you aren't attracted to every girl, he's not attracted to every guy.
If he does like you, it is more complicated. Realistically, if he is attracted to you, he might also be in love with you. This also probably sounds like a lot to handle. And it is, sort of. From your perspective you were just two guys who liked to do things together and enjoyed each other's company. And that's what your relationship is to him too, just that he also thinks you're a handsome bro. This does not mean he's constantly thinking about having sex with you. More that sometimes when you're talking, he's listening and interested in what you're saying, and other times he's thinking of how fucking sexy you are and not listening so carefully.
This doesn't take away from that great basketball game you played together, that crazy drunken night you had, any other experiences you've had, or the other personal shit that you already knew about each other. It does mean that he has effectively let you into another, deeper level of his life. It shouldn't be a "dirty secret" to be who you are and open about what you're attracted to, but unfortunately it still is for some people in many places.
You also might be wondering why he didn't tell you sooner. It could be because he only figured it out about himself recently. It could also be that, at the start of your friendship, he wanted to be your friend for the normal reasons, like that you had stuff in common, but didn't know how you'd react to the fact that he's not hetero. Even if you're comfortable with your sexuality and you are totally cool with the fact that your friend is not hetero, admit that you haven't exactly gone out of your way to be friends with gay dudes. And would you be friends with him now if you'd known at the start? You hope so, we hope so, but we don't actually know.
Regardless, does it really matter who he likes to sleep with? Does it affect you if he has a pretty versus an ugly girl in his bed with him? Why should it matter if you're attracted to the person he's fucking?
It doesn't matter. Reminding him of this would be chill.
You also might be wondering if he's legitimately "gay," or just "bi" or "confused". First off, he might not like the word "gay". Some use it, and others don't. Stick with whatever language he uses. Either way, chances are if he were bisexual he would have said so because, if anything, there's slightly less stigma associated with that. If you found out in some other way, then we can't say really whether that sign or rumor or whatever you saw "means" he's gay. You'll have to talk to him about it.
Speaking of talking to him, talking to him is probably a good idea. If you bring it up and he says to drop it, then that's fine. It means he hasn't figured it out yet or you misunderstood. But more likely he does want to talk about it to some extent. If for no other reason than to just clear the air—to say a few things that have gone unsaid for too long. You can ask that question. You should ask that question. He may think it's funny and it might be a stupid question. Yes, there are stupid questions. But you should definitely ask it. He'll appreciate that you asked, regardless.
So what's your friendship going to be like moving forward? Is everything going to change? It's only going to change as much as you both want it to.The main difference is now you have a new subject to make jokes about. Take it easy on the "homo" jokes at first though; you're still walking on fresh ground here.
If he told you, then count yourself lucky that you have a friend who trusts you. If he didn't tell you, then make sure that he can trust you.
A guy who likes dudes
* * *
I also made an audio version of this because it was so popular (thanks, y'all):
Edit: a hetero bro wrote me an email asking how to approach his gay best friend.