How can we gently convince old guy with Alzheimer's to quit playing?

[Bats]

I’m not sure if this question belongs here or in Home Poker, but the issue is more psychological than about the game itself. I’m an aging Boomer (59 years old) and play in a home game with still older guys (62-75, several retired) who have been playing together for over thirty years. I was invited to join the game 4 years ago when one of the original members of the group became too ill to play. It’s a typical low stakes home game with stupid games like Anaconda, and mostly for drinking beer and yakking. I really enjoy playing with these guys, but one of them, call him Bill, is getting senile. Bill used to be a decent player, but over the last year has begun to constantly make mistakes, big and little. Little mistakes like often betting out of turn or forgetting it was his turn or not dealing enough cards aren’t a big problem, we just gently remind him. But the last few months he’s increasingly done things like misread the board in Hold-em or Omaha/8, raise and reraise thinking he’s got the nuts, only to be told he doesn’t. We all do this once in a while, but he’s doing it several times a night and getting angry when we point out his error. Bill sometimes forgets he’s folded, then gets upset when the miracle flop hits his now folded cards and we tell him he can’t play them. Frankly, Bill is making a formerly fun evening into a tense un-fun evening.

The guys who have been playing with Bill for 30 years know he’s become a problem, but don’t know how to un-invite him because he’s a very old friend. One guy called Bill’s wife to try to get her to tell him he’s too old to play, but that went over like a lead balloon. All she did was go on about how much he enjoys getting together with his old friends. I can’t un-invite him because I’m still the new guy. Does anyone have any good suggestions on how we can gently persuade him it’s time to put the cards away? (Please, no jokes about just shooting the old horse.)