I know this type of person so well. They rely on you for when there's nobody ''higher status'' around to validate them. But when there is, oh boy, it's like they cannot help themselves, they are simultaneously fawning obsequiously over anybody they believe can validate them while icing you, keeping you at a bit of distance. Two personalities on the go simultaneously.
This situation has happened to me a lot and so I wondered what part of the equation I was fulfilling, you know, and I think it's that I put up with it. I have distanced myself from the fake friendships now. even if that means I miss out on some invitations now, so be it.
You mention a friendship with another woman who wasn't there. And I think this is your only solution, focus on individual friendships.
This woman is insecure in a GROUP setting by the sounds of it.
Go the opposite way. Nurture INDIVIDUAL relationships.
She's obsessed with appearing to be popular. You can focus on nurturing genuine connections with individuals.
Draw in other people. Was there anybody else on the outskirts of the love bombing? I bet there was. I bet those people are worthy of conversation and inclusion.
When this happened to me, I decided that harmonious inclusion was my goal and it made me mindful of the times I was included but somebody else was left out.