I can understand your concern. Does your POA document have a listed alternate? Most do. If not, I’d get a new one promptly. Whether you share that with your husband is a personal choice.

I’ve heard it is thought that telling the patient one time is customary. After that, it’s probably not helpful. I’m no expert. They will likely forget it at some point, but that’s an individual thing and you should do what you feel comfortable with. My cousin was told once by the neurologist and we didn’t discuss it again except, I’d say no one has a perfect memory. No worries.