Your brother is still a part of your family. You cannot change a person if you do not communicate with them. Case in point, my son-in-law has listened to me rag on about islam/muslims for years now. He always thought I was being extreme in my views. Well, after many years his light bulb on been turned on and he realizes what islam really is now. Try not to give up all hope on your brother. He really needs your help right now.
Just my two cents.
My brother is still a part of my family, but I don’t want to deal with the dynamic of being polite to a family member who is rude in front of my children. It’s much easier, for now, to simply exclude him from family events in my home.