I feel really bad

Basically I am feeling really REALLY guilty because last night, my best friend invited me over for some beers, we got very drunk together and he started to get kinda weepy and upset. In comforting him, I started rubbing his back telling him everything would be ok and so on. He is straight by the way, and he has a girlfriend. This is why it makes it this much harder to reveal what happens next... he then sat up from my lap and said something along the lines of "you know I love you bro, you're my best friend and.... if I were ever going to have a gay experience I'd want it to be with you. and now." Keep in mind he also doesn't even know that I'm Bi, but I feel like he kinda got the idea that I was. I've never hit on him and I respect that he has a girlfriend and everything and NORMALLY I would never do anything to interfere in their relationship. But he goes ahead and kisses me. And I'm like "woah! ok one second here I'm confused". We stop but then, being drunk and horny I just go with it. He literally ripped off my shirt, We make out and I proceed to give him head and he gives me head too... really passionately. after this we agree that we will both never speak of it again and it's not happening again. I know I will not do it again if he's in a relationship because I feel honestly so terrible about it right now. I'm also really worried people will find out, what if he gets drunk and admits to his girlfriend? Or anyone? I am worried it will get out but pretty sure he won't tell anyone because he is, as far as I know, straight. and I think he wants to protect that image. But basically now I just feel like a really terrible person and I wish I hadn't done it. At the same time. I kinda want him. We have this crazy good connection and I've always kinda liked him but we've always stayed strictly friends until now. I feel like he is not going to want to hang out with me for a while now, but I'd like to carry on as normal. Because we usually hang out at least twice a week. Any advice??? Stressing out here.