I was friends with someone for several years, we got along well and saw each other often but were not BFF or anything. Suddenly me and a few other friends noticed him making hateful remarks where he never had before, and we asked him about it.
He had gotten imbroiled in an organized hate group, not sure how, but it happened. Me and the other friends quickly droped out of his life after he started targeting us because we had "dirty friends" (his words not ours), we tried to discuss this with him, but his mind was made up, and he expected us to change to suit him, and could not understand why we would not change. It was very difficult, and he was just a casual friend. I cannot imagine how this must be hurting you.