Taking you at your word, it sounds like an honest mistake so my advice is don't tell him - he'll never get the images out of his mind.

Get tested for STDs. If you did catch something, you'll need to tell him.

Of course, don't do it again!

After 5 years of marriage my first wife confessed she had sex with another man, just the once. She really felt guilty about it.  I asked her all the details and she told me he went down on her and she had an orgasm.  She told me they used a condom.  I was devastated and I did not think I would ever get over it.  I did learn to enentually cope with it and in the end I used to think about her having sex with this other man when I was having sex with her.  In the end it started to turn me on.  I believe she thought it was a mistake and that is why she confessed, she did not have to tell me, I would never have known.  Although I did not like my wifes confession I was glad she told me.  I think you should tell your boyfriend or it will haunt you for years.  After all, you are only human and just made one mistake.  All the best.

 That secret will haunt you for the rest of your time together. Your guilty conscience will eat away at you everyday. If you can get that drunk and spread your legs for some fucken random dude to blow his load in you then I would bet that you will do it again everytime you get drunk. Hopefully you get checked for Herps, syphlis, gonareah, warts, aids. Hep a,b,c. Seriously think about it your in denial and that's why your posting asking people if you've fucked up, Yes you have and the only way to clear your guilty conscience is to be true to yourself and your sorry ass boyfriend that is going to be devastated when you tell him that your a fucken pig that you cant be trusted when you drink. Tell him you SELFISH slut and see if you two love birds are so happy together.

Dont tell him just leave him. You dont deserve him. Go somewhere far away. Do whatever you want just dont bother him anymore. He'll be better off with you not telling him about it i can tell you that

Human sluts

You have these outcomes... 1) You can tell him now, and he will probably leave you. If he doesn't, the relationship will die a slow death from trust issues, and the pair of you will break up anyway. 2) You do not tell him now, but as your conscience is bothering you, you will probably and eventually tell him later. So 1) happens later than sooner. 3) You do not tell him, and someone else who knows leaks ot to him, and 1) happens later than sooner. 4) You do not tell him, and somehow, he never finds out. Then a) you can live with your guilty conscience forever, or b) given the greater probilities of 1, 2, or 3, you leave him now or eventually because the probability of your relationship would not work out. Hence, your possibility of having a successful relationship is small. By estimation, a long term loss is best terminated immediately. The probability of success here is so small, it is optimal to break up with him as soon as possible giving him some other reason than what you have done. Some may say that the truth will set you free, and your conscience will be less burdened. However, your less burdened conscience is at the expense of torturing this innocent man who loves you. It would be advised that if you love him, do not torture him, and be merciful. Scuttle the relationship by some other method in the least painful way for him. 

Well a slut is always a slut, you can't change that. Unfortunately you will always be a whore and there is nothing you can do about it. One a lady cheats on her husband or boyfriend there is no going back. You need to tell him what kind of trash you really are and if he haves half a brain he'll throw your shit out the window along with all the other trash. The best advice I can give you is you should probably go kill yourself. Do it now before you drag innocent children into the mix. It's a shame that men get this bad wrap about being cheaters when whores like you are always looking for the next big dick to come along. Goodbye slut! 

I moved cities to go to college. My boyfriend stayed home and we stayed together. We're in love and want to get married and have kids. He talks to me constantly, but I miss him every second. Missing him makes me feel sad deep down. My first couple of weeks were really rough. I had no friends, I was really lonely, I felt like I had no purpose, like I was just taking up space and I was really lost and confused. I saw my favorite dj was coming to town and wanted soooo badly to go out and have a good time. My soul needed to feel itself again. The only person I knew that was going was a guy from my past (before my boyfriend). I figured "I can go, have a good time, and come home after". Well, he gave me alcohol before the concert and I don't really drink. We got there and I danced with him the whole time...then when we left I kept repeating myself that I wanted to go home and that I was tired. He said "no you have to come back to my place because you left your purse there." This was true. Then I knew, shit this is a sticky situation. When we ended up there be kept pressuring me and pressuring me to just TRY cheating and that he would never have to find out, etc. I was really confused because I had a huge crush on this guy in the past and never got closure. I kept saying no. But it's almost like I got annoyed and just wanted him to stop pressuring me. So I sat on his bed where he was. He started to kiss me. We kissed for a few seconds and I immediately said "I feel guilty already!" And I ran home. Nothing else happened. But now I feel like I've cheated on the best person I've ever known. Not a soul knows besides the guy and myself. I can't lose the love of my life because of one douche bag and a stupid mistake! But the guilt kills me. I can only hope in time I will forget and nothing will ever come of it. 

Your'e not a victim here girlfriend. Don't paint yoursef as one. You dlinerately chose to drink, you consciously chose to have sex with this other man. If you had any respect at all for your BF you would have told him. This poor man has a GF that may fuck some guy when ever you drink too much. He doesn't deserve you at all.

I know this is an old post. If you can stop drinking forever, then do so and don't tell your boyfriend. If you can't stop drinking forever the tell your boyfriend about the other guy.

If you were really so drunk that you couldn't stop yourself from fucking another guy, then you were so drunk that you would have driven drunk, and possibly killed someone, or you were so drunk that you might have walked into traffic and been killed. If you weren't the so drunk that you wouldn't done the other things then you weren't so drunk is that you couldn't stop yourself from fucking the other guy then You're just using the alcohol as an excuse.

Giving you the benefit of the doubt, and assuming that you were really that drunk, then you need to stop drinking and you need counseling.  Fix that, and there is no need to tell your BF.