Toxic family member - what would you do?

My uncle is very religious and strict, and he married a woman almost exactly like him, except she’s not very socially adept. The rest of us in the family are much more secular.

They have isolated themselves and their son from our family for many years. They’ve started fights at family events, because we had a bottle of wine, or a few beers (so they call us alcoholics.) This is the same uncle of mine who told me not to sing Black Betty with his son because it was racist. He ran an elderly neighbor off, who has a mental illness, because he cussed too much.

His wife’s family, although having their own problems, is fully acceptable and they send their son over there constantly, which some of us find very hurtful.

Would you just cut him/ them off after years of trying or how would you handle it? He doesn’t want to communicate any real feelings or emotions, it’s just blaming our family for everything, including their isolation from us. It’s hurting my mom a lot, and I don’t know what to say to her to make their rejection less hurtful.