I just typed up a whole thing about D20 skipping her drive-through Covid graduation, and how a year and a half later, I can say it honestly didn’t matter. We supported her choice and focused on moving forward.
I deleted it because your situation is so different. I read your past thread when it was current and reading this one, I am struck by how much hurt and anger you have towards your family. I know you feel justified. I am going to urge you to get some counseling and think long and hard about what you want long term. Some burned bridges can never be repaired or replaced. It’s easy now to think about yourself and not worry about hurting your parents but you need to think about what that might look like when you are in your 30s or beyond. At the very least, you need to learn how to deal with your feelings so you can be a good friend, partner and (maybe) parent in the future.
Sure, the ceremony is a few hours and may not matter much (we don’t feel like we missed anything by skipping D20’s) but I think you need to consider the long term effects of the damage this does to what remains of your relationship with your family. Good luck to you.