i had a similar expierience when I was a bit younger ,,,, well not really ,, but it was kind of the same ,,,
I was at a party with my girlfriend on my birthday and I was loaded, as everyweekend and she was pretty drunk ,, anyway ,, when I'm drunk and stonned at the same time ( which is every weekend) my eyes look like they are closed shut but I can see everything that goes on around me perfectly ,, anyway she(gf) was talkin to me and I was loaded and shit and couldn't talk ,, then she just laughed at me and kissed me then she sat by the side of me and started drinkin whatever she had . About 30 minute's passed,,, she got up and left the room ,,, then a couple of my friends came in and sat down drinkin ,, they thought I was asleep ,, anyway my gf came back in and sat down and started to talk to them ,,, then three of them left and went up stairs ,, and thats the last I saw of them for a couple hours ,,,, I somehow managed to get out of the room and go to the kitchen ,where I was told what my girlfriend and my "friends" were doing up stairs,,I stayed calm for about 20 minutes ,, just sat there and took part in some weed smoking . Then it just kicked in what was going on and I flipped ,,, being the drunken fool I am ,,I started for the stairs ,,, on my drunken halfway's up (stairs are bad when drunken) I came across one of my "friends" comming down ,, who immidiately turned around and walked back to the room and I geuss announced my pressence ,,,, anyway I, still a bit drunken and fried out of my tree couldn't make it up the stairs so I sat on em for about 20 -30 minutes . I was awoken by the slamming of a door and foot steps behind me ,, well lets just say I greeted my bastard so called "friends" with swinging closed fists ,,,,, nothin like rage under the influence ,,,,my "girlfriend" got afraid and called her mother ,,,, and about 20 minutes passed and my real friends were tryin to stop me from beating the living shit out of my not so real friends, who were up stairs and wouldn't come down ,, so to there luck the cops showed up and we all had to leave that crazy place ,, so me and my friend and his step-sister left the party around 1:00 and went to get something to eat ( I think) ,,,,after that me and my friends step-sister went to the glynmillinn trails (walking trail in corner brook) walked around and talked about what happened ,then we smoked what I had left and stayed there for a while ,,,
I don't know how that story was similar to your's but whatever .
to make a long story short ,, my 2 good friends fucked my girlfriend on my birthday and I flipped at em and broke some body parts,,it's amazing what you can do when your pissed off ....
and the lesson learned from all of this
Sometimes you might find a girl that you think you would do anything for ,, until she gets drunk and fucks your two friends on your birthday.
Basically