ScottfromWI said it best: "You could have not gone in the first place. You could have left when you realized they were serving alcohol even though you checked it out ahead of time. You could have ordered a soda or water. You could have said no thanks."
I think Justin, it might help to change your habits that go along with drinking. You went to an "after work party"....and those usually involve alcohol. I remember trying to go to bars early in sobriety and just drink Sprite. It was probably because I felt comfortable in that environment. As long as the person I was talking to had a beer in their hand, it felt like home to me. But that wasn't a great idea, looking back on it. If you really want to give yourself the best chance (and it sure sounds like you do) it might be good to stay home from these work parties from now on. And that live band on Saturday night. And the Super Bowl party too. Give yourself a chance Justin, and be a hermit for a weekend or two.