The most ridiculous thing happened to me.

Friday night I went out with some friends, got black-out drunk and passed out on the couch of my best friend and his girlfriend's apartment at about 12:30am. The first thing I remember since blacking out is waking up on the floor of their apartment not knowing where I am and shaking uncontrollably with my friend standing over me. I made it back to the couch and fell asleep. When I woke up on their floor like that i was like "that was a crazy dream". Inspired by just finishing the Da Vinci Code that day, my dream was about me being Robert Langdon starting to have sex with Sophie Neveau so we could keep the blood line of Jesus Christ alive (weird i know; I often have really strange dreams). I had to leave early in the morning because the parking meters started charging and i didn't want to get a ticket so i drove home. By that time i was sober. i hung out at home watching movies all day Saturday with a bit of a headache and feeling tired. at 8pm that night i got a text from my fried saying "WTF was that?" I was like i don't remember anything except waking up on your floor shaking. Apparently he said I got into bed with him and his girlfriend at 3:30am and started touching her so he pushed me off the bed. I don't remember any of this and my memory only begins when I woke up. But i do remember being confused as to where i was and thinking that i just had the craziest dream. I had no idea that i was in their bed or touched her. The only way i could explain this is that I was sleep walking since my memory starts as soon as i woke up from falling on the floor. I didn't even know that I fell off the bed. He's pretty much my only good friend and we've known each other for years, and I don't even like his girlfriend to be honest, so I would never do this to him. Plus if I actually wanted to do this with her I wouldn’t have done it right next to him. What's worse is that I'm engaged to the most amazing girl in the world and would never think about cheating on her. We have been long distance for a while, while she finishes school and she is just about to move out here next week, so it doesn't make any sense. I know I was blacked out before, but I remembered waking up on the floor so i wasn't blacked out then and I had slept for about 3 hours. I don't know what to do. I don't think I can ever face them again because I'm too ashamed, but I honestly wasn't conscious for it. I don't know how to tell my fiancee. Is it possible that I was sleep walking and did this? It seems crazy and unlikely, but I honestly have no other explanation. Does anyone know anything about alcohol induced sleep walking?
Ive never considered myself an alcoholic because I almost never drink. I never have a casual beer by myself, and only occasionally get one social beer at happy hour with friends. I probably drink once or twice a month on the weekend but only a few. sometimes I go months without ever consuming any; not because I think I have a problem, but just because I dont really drink often. However, a couple times a year when its a special occasion and I know everyone will be getting drunk and I dont have to drive, Ill keep drinking and dont stop and end up blacking out (which is usually after the magic number 6 drinks). I think part of the reason why I have trouble stopping once I black out is that I have social anxiety so I have very little social contact with anyone, other than video chat since my fiance and I have been long distance, but when Im drunk I can talk to anyone. It gives me a confidence I can never normally have. Because of my social anxiety and the fact that Ive been long distance for so long with my fiance, maybe there was a subconscious desire for physical contact, even if it was with this girl I dont like. So I think I should stop drinking before something worse happens, but I dont think I can go to AA meetings because I drink less in a year than most of those people would drink in a week.

Also, I remembered back in college I would sleep at my fiancee's dorm and she had two roommates that slept all in the same room. often we would get up and have full conversations and the next morning neither of us remember. I have woken up in the middle of the night making out with my fiancee, but go back to bed realizing that she isn't kissing me back.

Ive apologized to my friend, but am terrified to tell my fiance. But I have to tell her because I cant live with this bottled up and trust is such an important thing with us. This is so bewildering and I dont know what to do.

Any supporting comments would be helpful because I am so ashamed and discussed with myself but I don't think I could have stopped myself since I was sleeping.

Bssleepwalker,
First let me say that I have no professional expertise in this area, but I do have significant personal experience in situations very similar to yours. While I suspect that the causes behind this type of unconscious behavior are complex, alcohol is undoubtably a contributing factor. I think is it safe to say that, however infrequent, alcohol a part of an unpleasantness in your life. I have no doubt that you would be welcome at an AA meeting if you chose to attend. I do think it is wise it examine your relationship with alcohol.

This is not sleepwalking and I suspect it will reoccur if you continue to drink heavily.

In my experience these episodes tend to be sexual in nature. In a mild situation, the person might appear to be awake and aware and may communicate rationally with only slight signs of impairment. In this mild scenario, it may be possible to rouse this person almost immediately and they will have no memory of this event. In a more grave situation this person will be move but appear to be minimally conscious, clearly impaired and with minimal awareness. In this situation, this person may or may-not be able to communicate, verbally or otherwise. It would be difficult or impossible to rouse this person for several hours and they will have memory lapse of 8-12 hours or longer.

My advise it to treat this as the serious and complex situation that it is and seek support from friends and family, as well as considering professional counseling.

If you do not address this issue, you may unintentionally cause physical and emotional distress to people you care about. I seems as though you may have already, or at least strained a friendship.