There's not a huge amount of detail so I can tell if YWBU or not. How old is your daughter? Was this drinks that was reallly for the girls only and parents weren't expected to stay unless they felt like it? Would you not normally talk as part of a group to these women at other events or at school? Is your usual routine in front of these women NOT to stay, and hence they didn't get you a chair because you usually just leave as soon as you can? If you usually refuse to stay, have you ever thought that you may cause other people to feel uncomfortable or rejected or not worth your time?
I do have sympathy. I'm an introvert who grew up feeling very anxious in social situations. I prefer just one or two other friends to spend time with, I'm not keen on large group events, and didn't enjoy parties until I was late teens and even then I would fret about stuff. To be honest even now I'm not totally relaxed around people I don't know well, or at all, till I've had a couple of drinks. I'm also perimenopausal and the anxiety is hell, I agree. But when my kids were younger, I really made an effort for their sake even if I felt uncomfortable. I used to talk myself through it "what is the worst that can happen if I sit down and no-one talks to me, and what will I do? I will get my phone out,check my messages and if I still feel ignored even if I myself have tried to make conversation, I will make an excuse that someone has messaged about something or I have a headache or appointment or something that leave." Once I knew I had a solution to a problem if it crept up then it relieved the anxiety a bit.
Gradually you learn the little phrases and actions you can take when people are being a bit dense wtih taking the hint about things like needing to find an extra chair. eg "Room for a little one?" if a chair was nearby and pulled it up. Or just found the person you get on well with most and asked them how they are/what they've been up to. Or ask them something about school.
Basically, I don't want to make other people feel uncomfortable by MY discomfort so I fake it till I make it type of thing and 9 times out of 10 the conversation will start to flow more naturally and I find myself relaxing.
Of course, real mean girls will always be mean girls and you soon get to know which are mean girls and which are women who just don't know you that well and are unsure how to take you.. I don't bother if I feel real mean girl vibes - just wouldn't want to waste my time on horrible people like that.
But you know, most people aren't horrible. And worth a try sometimes. Because one day you will HAVE to be the host or someone close to the host eg at a loved one's funeral. Or attend a confrence or training event where the dreaded networking is expected. You just can't dash off and hide in those kind of situations. (well, maybe at some work events, just for a little while. 😆