I Messed up Big Time with straight friend

This seems like a pretty complex situation, so I thought I'd offer a few thoughts and observations:

I'm a little concerned about what seems to me a premature assessment of the situation on your part. You seem to have convinced yourself that nothing but bad things have come and will ever come from this encounter, so therefore you should avoid his advances at all costs in order to avoid a repeat situation. I don't think that this is the case at all.

Under your worst-case scenario, everyone your friend knows finds out about the encounter and he commits suicide. Let us rationally consider the evidence you've presented so far. When your friend hit on you a while back, he avoided you for weeks because, presumably, he was very ashamed about his actions and his attraction to you. Seems like he was a pretty big emotional wreck at that time (not to imply in any way that questioning your sexuality is not a legitimate place to be; it really is). Instead, he just ran from the problem until it essentially went away. Now that he has actually acted on those unacknowledged feelings (yes, he most likely got drunk in order to give himself indirect permission to act on them) and he's gone beyond the furthest he's ever gone with you, he texted you about it the next day. Granted, he probably brought it up in large part because he was worried that you were going to tell people about what happened, but I think your friend's actions show some progress on that front. If he was in as much denial as he was previously, he probably would have just denied that anything happened; he could have said that he was too drunk to remember, which would have placed the blame entirely on your shoulders and not the alcohol and his horniness.

Indeed, some positive things could come about as a result of this encounter. And I'm not talking about your best-case scenario in which you end up together and live happily ever after, either. Advice columnist Dan Savage once said that it is a lot harder for closeted people to remain in the closet when they keep acting on their repressed desires with willing participants (just paraphrasing here; I'm sure he was a lot more eloquent). This line of thinking makes a lot of sense to me. Your friend, undoubtedly, will now have to explain to himself why he keeps ending up in bed with other guys. He'll probably just blame it on the alcohol this time, but there are only so many times you can end up having sex with a guy before you really start doing the kind of soul-searching that coming out of the closet requires. I guess the counter-argument could be made that, if your friend can get sex without having to come out or even just acknowledge his clear attraction to you, then he would have no incentive to ever do either. I would respond that people usually do not come out until they are at least pretty sure about their sexual orientation, meaning that coming out usually also has a sexual experimentation component apart from the soul-searching I mentioned. People like to be sure before they take such a big step. In that sense, you could have given him a small push in the right direction towards a more honest place.

And this brings me to my next point: if you find yourself in the same situation where he initiates sex with you, I think you should definitely go for if that's what you want to do. If you feel that he's just using you and could never care about you the same way you care about him, then by all means spurn all his future advances. If you just want to have sex with him and he also just wants to have sex with you, then it is perfectly acceptable to do so. It would not be selfish, in the least, on your part. I think your reluctance to find yourself in bed with your friend also has to do with some residual guilt. I will say definitely that you shouldn't feel guilty at all about what happened. You both got drunk and had some sexual contact, which is exactly what happens at every college/university every single weekend. You should also not be so afraid to replay in your mind the exciting parts of the encounter as many times as you wish and get off on them. It is your right and part of what makes sexual experiences enjoyable.

At the end of the day, these are just my thoughts and conclusions; only you can decide how to move forward, especially since only you have all the facts, or at least most of them. Sorry if I was a bit long-winded, but I do hope that this helps, even just a little, by putting some things in perspective.