AIO for refusing to participate in my sister's wedding over her dress code demands?

Well here is my situation. My sister, (25) is getting married next month, and I (22F) WAS super excited to be a part of her big day, until now.

She recently sent out a detailed group message with a bunch of "rules" for the wedding. Most were normal stuff, but then I got to the part about the dress code. She's insisting that all female guests wear floor-length gowns in specific colors and we have to wear heels but those heels can't be over two inches to "ensure she stands out"

Okay, reasonable but here is where it becomes a pain in my behind. I've had an issue with my foot for almost two years now and I kinda have to wear orthopedic shoes. Lame, I know. I let her know and suggested a compromise like something along the lines of wearing flats that match her color scheme, but she said no and that would be "ruining the aesthetic" of her wedding.

We argued, then told me that if I can't stick to the dress code, I shouldn't come to the ceremony at all. I told her that I thought this was unfair and incredibly inconsiderate and now she isn't talking to me. Even my mom is siding with her but to be fair she has always been the favorite. I really need to hear some opinions from outsiders because it's honestly stressing me out so much. Any feedback would be very much appreciated.