Guys, thanks for the comments and encouragement. It's 6:30am, now awake with no hangover, and really, that alone justifies missing the party.
It would of been so stupid to spend those few hours drinking, I would of added nothing of value to my life, but maybe next party I will have the strength to go and enjoy the company of these people and also the grilled Argentinian steak (and dessert of chocolate fondant), mmmmmmmm !
It also reminds me that drinking only ever leads me in one direction. There's no option to attend a party and drink a few, I would get drunk and then it would just progress until I was drinking every night again whether I wanted to or not, which leads to me being more miserable and wanting to quit. Its like Groundhog Day without the comedy...
Anyways, thanks all