My partner's sibling is having her wedding soon (I believe in less than 6 months), these are only plans. The groom to be wants a huge, luxurious wedding while the bride to be does not. He always gets his way (and to me sounds like a red flag but this is beside the point). I was told since I'm close to her that I might be one of the bridesmaids. 

I had an unexpected anxiety attack. Not only do I deeply dislike huge social events, the whole pandemic has instilled in me more anxiety about gathering in large groups, I just never do these things. 

How can I cope with this? I feel like I cant refuse as we are basically neighbors and her brother (my partner), while he agrees he dislikes the whole extravagant thing and hopes his sister gets a say, will attend.