I am no expert, nor a psychiatrist, or in any position to offer advice. However, I was in the same position as you. My stepfather was the abuser.
I can promise you that if he attends your wedding it will be spoiled for you. At all costs do not allow him to be there.
I can promise you that if you chose to tell everyone about the abuse you will have tremendous support. I was told to hide our family dirty little secret, and for years I did, and it slowly chipped away at my confidence, self dignity and ability to love myself and others. The act of keeping my abuse a secret for the sake of the family, poisoned me. The day I took control of my own destiny and refused to continue protecting the abuser I felt liberated. I told people, and not a single person was disappointed in me. Most cried, they had known me all my childhood life, and I guess they blamed themselves for not seeing it. A users are very good at manipulating and hiding in the shadows.
Since taking that brave step to tell the world, I have NEVER had to see him again. My mother was pressured to leave him. My wedding was fabulous without him. Christmas Day became a day of joy. Etc.
Your family will forgive you for exposing the secret, eventually. Even if it takes them some time to get over it, you will be free of his mental torment forever.
You have done nothing wrong. You are an innocent survivor. Nobody has the right to tell you to keep it secret to protect family. I was in your position exactly!
If you honestly are not ready to expose him. Perhaps, talk to him and tell him to tell everyone he is sick on the day. Tell him that if he dare show up to your wedding that you will expose him right there in front of everyone.
By protecting the family image, who is protecting you?
Anyway, I empathise with your situation. It takes a lot of strength and bravery to expose a family member of abuse. The risk is high. You may lose some family. But a family who will not support you is not a true family. They support him! Why not you!
You have a husband now (soon). He, and his family, is your family going forth into the future.
If you cannot expose him, and there is no way to avoid having him there at your wedding, try to seat him as far away from you as you can. Destroy wedding photos with him in them. Focus on your wonderful husband. Try to forget the monster is there. Wrap yourself up in your husband and the wonderful wedding. Enjoy the many guests who are there with your blessing.
Only you know what is best for your situation. For me I had to tell everyone before my wedding. It was incredibly hard, but once I'd done it, the relief was liberating. I've lived a better life since. But, it did take me a few years to muster up the courage to expose him.
Remember you are 100% more important than him. If he does attend your wedding, ignore him and don't give him the satisfaction of spoiling your day. He's not worth it! He's nothing!
Not sure if I've helped any, but being in such a similar situation, I felt my story may help some.
You are worth the effort.
Debbie