Pride Story

So I'm stuck in a bind and I don't know what to do. I'm gay and I'm open about it, I have been for almost 2 years. I've had relationships before. The problem I'm having is with my best friend, let's say for the sake of telling the story his name is Kevin. He's been my best friend since i started college basically, we were roommates my first year and will be again in our third year. He's been dating this one girl Erica for like two and a half years, she's very sweet and I love her she's awesome. But a huge part of me thinks that 'Kevin' is hiding something... For one, he and I are practically twins, not a single day goes by where we don't say the same thing at the same time, or we're thinking of the same thing. We both work at Hollister and he buys more clothes than I do, he always talks about how much he loves buying them. He recently bought a bunch and was dying to show them off to me. He loves to lady gaga, beyonce, la roux etc... lol although he also likes a lot of rock (of course I do too, I've even gone to heavy metal concerts). Those are just some of the things he does that raises question.

At this point its possible that he could be straight and I just want him to be gay or bi in my mind. But there was this one night where he and I got drunk together in his room, his girlfriend was gone so it was just us two. We got really smashed and he ended up pulling out his fully hard dick, I remember him saying "See this? this is Erica's dick"
and I remember saying "No it's not it your dick"
and he replied "Nope it's Erica's"
then I said "What about if I want it?"
After that he smiled then giggled at me and went to use the bathroom (we had a lot of alcohol so there were frequent bathroom breaks)
things started getting foggy at this point but I remember one point in the night I was leaning over a trash can in his room in between throwing up and he was on his bed watching me, and i'm almost certain I could hear him saying "I really want you fuck me in the ass"
"Let me finish throwing up and brush my teeth" I remember mumbling
"hurry!!"
After that it went foggy again so i have no idea if we did anything. Next thing I know I wake up at like 10 am in his bed, I'm completely naked and he has his boxers around his knees and we're spooning, My dick is pressed up against his ass. I felt something warm and soft in my right hand and i Realized I was holding his dick. I was still a little drunk so I started stroking his dick and it started getting him hard. He was semi conscious and he reached back and started trying to shove my dick into his ass which wasn't working because we had no lube lol. I remember really wanted to suck his dick at this point but i was enjoying myself kissing the back of his neck and humping his ass too much, I knew he was enjoying it because I could kinda hear him moan. Then after about an hour of this I had to use the bathroom so I got up to go and came back and he had put on his clothes and gone to use the other bathroom. When he came back he claims he had no memory of anything that happened the previous night or being naked that morning just 20 minutes earlier. After that I kinda let it slide deep down I pretty much KNEW something was different but I let it go because I didn't want to force it out of him.

Now lets bring it up to present day...
It's been almost a year since that day we got drunk in his room, I haven't been drunk with him since, Every time i ask him he says he doesn't feel like drinking, (My theory is that he's scared of a repeat or scared he'll tell me too much idk) But about two and a half weeks ago after a night of hanging out with all of our friends (we both had a little to drink but not enough to get us drunk) both of us went back to our apartments and I get a text from him saying "I need to tell you something"
Naturally this gets me a little excited, so I told him that he can trust me with anything because I trust him.
"I think I might be bisexual" was his next text...
so i go on to tell him that his secret is safe with me and that i kinda knew since that one night we got drunk together. He replies with a bunch of "lol"s and such not talking a lot. He also asked me what it's like to have sex with a guy so obviously he's thought about it. I tell him that it's pretty awesome lol just to kind of make him laugh because I know it was hard for him to tell me all of this.
So later we both go to sleep and the next day I text him asking him if we can continue the conversation we were having. He said alright but his attitude kinda changed, he went from saying he would catch himself thinking dirty things about guys to saying he doesn't really know why he thinks he's bi.

At this point I don't know what I should do... I feel like he's trying really hard to hide it because he doesn't want to hurt Erica, I know he really does love her, I just don't know if he loves her intimately. If he's genuinely bisexual then there isn't a problem and he should just tell me and let that be that. If he's gay then I can see where that would be hard, I think he might be holding back telling me because he's afraid of me trying to push him to come out or to act on it. Which is not what I'm about I just want him to be honest with me. I mean yeah he's my best friend of course I do have some feelings for him we have a shit ton in common. I'd be fine if we were to stay just best friends I just want to know I guess lol

What do you guys think? Should I wait and let him tell me on his own? should i talk to him? do you think I"m right about his sexuality? lol