If you know in your heart you are going to have a tough time...don't go...you can beg out of the office party by coming down with something unexpectedly :-)
If you feel up to it I find having a beverage at all times helps. People are less likely to ask if you havens glass of tonic water in your hand already (how do they know there is no gin?). For the drunk a$$ who keeps trying to buy you a drink a smile and a "no thanks, I'm good" is enougg...plus you can appreciate what a douche he is being.
As For friends I have told them I no longer care for the taste or the way it makes me feel. This is the truth, just not all of it, and I have never had to explain myself in greater detail.