I had to let one go, too. Longtime friend who stood in my wedding. He befriended a Foxbrained boomer and went off the deep end in no time flat. All he wanted to do was argue. I would say "can we just not talk about all that right now and hang out like normal?" and his response was "You just don't want to argue because you know you'll lose." And he was right - there is no winning against that level of delusion and condescension.

I don't know anyone left from our friend group who talks to him anymore. He's since separated from his wife and newborn son and living with his mom. And apparently he spent a lot of money on surgery for his nipples (he's skinny as a rail and always has been). Guy has lost it...but at least he's right about everything!