I work with patients that has dementia, been doing it for 4 years now.
If there's anything you wanna know, you can ask (even tho I don't know everything^^).
You should have a support system, someone to talk to that can try to guide you and your husband thru it, as well as help him on a regular basis, so that all the responsibility isn't on y'all.
If he goes to a home, try to make him a photo-book, with pictures but also details about the pictures, to help him remember - names, dates, places, maybe something funny that happened, life-events. Tell the caretakers to regularly hand him the book, and maybe look thru it with him.
If he has any hobbies, or had any hobbies, you can try to introduce that back into his life. I have one patient that used to paint amazing pictures when she was younger, and she has them on her wall. So I got her painting supplies, and every time I'm in charge of her group, I bring it out and write down what she should paint, this has made her sit up after breakfast and paint, then talk, read and stay social, instead of going back to her room to sleep the whole day (she used to do that because she was bored).
With communication, it can be tricky and everyone is different. I have some patients that I can rationalize with, others I just go along with their pov. As an example, I have one patient with psychosis as well, and whenever she gets angry about something, instead of telling her she's hallucinating, I'll go and say something like "Aaagh, that's so annoying! I totally get why you're mad, they're idiots right?" then when she connects with me (on her level), I'll bring her back down to my level by asking her to get a coffee with me, so we can talk about it (she loves coffee), we then go sit down, and by the time she has her coffee she's no longer angry, and can talk about something else.
I've told families that "if she's on a boat, so are you and we'll get there tomorrow", and it's usually always a bit surprising at first, because it's hard to understand how someone can sit in their room and think that the boat is moving too fast. But sometimes you have to join them into their reality to be able for them to connect with you in your reality (if that makes sense).
It's hard, specially when it's a loved one, so make sure you take good care of yourself, and don't feel guilty for checking in with yourself and asking what you need (and doing that).