I can definitely relate to being annoyed w/drunk people. Thanksgiving and the funeral I attended a few weeks prior were perfect examples. I was absolutely fine with attending the events, drinking wasn't necessarily a huge part of them, but there were people still drinking.
Stayed at each event for about 6 hours. Both distinctly had one person drunker than most, becoming increasingly annoying as time went on. Funny thing is, that person used to be ME. As the night wore on, I remember both events hitting a "line" so to speak where I just say "alright, that's it for me, thanks I'm out, PEACE" and left. Felt kind of awkward to do so, but I felt it was time to go.
You are allowed to excuse yourself from situations that make you uncomfortable.