Hi and welcome Strength
The best way to resist pressure is to have a strong sober support base to call upon.
I'd also be a little bit careful about what invitations you accept and, while I don't recommend the whole 'HEYS GUYS I'M AN ALCOHOLIC' speech, I think it does no harm to let people know you're having a dry Xmas - I personally don't think you need an excuse at all, but many people use 'health reasons', 'on a diet/trying to get fit'.
There are some good tips on staying sober at social occasions here (don't mind the title)
Crying Out Now: Thanksgiving Survival Guide
I never thought I'd have an alcohol free Xmas...I must have 8 by now...
You can do this
D