Sorry in advance for a long post! A friend of mine, A, has been having a protracted mental breakdown (compounded by substance abuse) for the past year or so, as a result of a bad break-up. Over that time she's been kind of a crap friend, but we've made allowances because she's been going through it.
She had a drunk row with another friend, B, at a wedding this summer over something silly, but B was pretty p*ssed about it.
A few weeks later, B made a group for her 30th birthday. We were surprised to see A's ex (who precipitated the menty b) on the guestlist - he's not a friend of B, and though they are acquainted, it looked calculated. A, who is not mentally well, obviously flipped and sent a long message saying essentially "f- you, how could you do this". B replied with "this isn't reasonable. I hope you get the help you need". And then blocked A on all socials.
To me this seems extremely cold and mean, especially given B knows everything about how much A has been struggling with her mental health.
My question is - do I still go to B's birthday? Or should I rally behind my friend A and make excuses? Part of me thinks there must be two sides to the story but I'm really struggling to figure out what B's could be.
YABU - just go to the birthday and stop getting involved.
YANBU - B sounds like a b*tch you should boycott the birthday