I think that you made the right choice by going. AA is an important part of his life as are these people and if I understand it, it's a long road that he's on there and being part of that journey with him would be helpful.
The main piece of advice I would give you though is to "sparkle" when you're there. As hard as it may be, pretend you are having fun and get to know people. I find the best way to make small talk is to try to identify what the other person is interested in and let them drive doing validation practicing to keep them talking. Don't hover at H and do your best to ignore OW or pretend that she's the "good twin" without being rude. You may want to pre-set a deadline of when you want to leave and get H to agree to it and / or perhaps some sort of safe word that if "either" of you are getting uncomfortable you can have a plausible explanation for excusing yourself.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells
