My husband will be leaving hospital tomorrow. He thinks he is coming home. But he is not. We are transporting him directly to a memory care center. (The alz has not progressed yet to the point where he doesn't know where he is and we are hoping for s amooth transition without him getting really upset because he is not "going home.".
You can say that he is moving to a different care unit to get better. This is not a lie. And it's not too much information that would be upsetting.
These days, hospitals are only to get people out of crisis and then get them discharged to somewhere else for the longer term care. You almost never hear of anybody who has a 10 day hospital stay for routine surgery, birth, or recuperation anymore.
He will have the same questions over & over, so don't feel like you have to give the "court accurate" version of the answer over & over. You only need to say enough to satisfy the question of the moment. And you will need to learn how to say things in a way to keep him calm even if it's a therapeutic fib.
My mom doesn't know her brother passed away recently. She's in an advanced stage of dementia and on hospice. When she asks about her side of the family, I only say that "everybody loves you and wants you to feel better". I don't give a recount of individuals and I certainly won't disclose any upsetting facts.
I look at it this way. It doesn't matter if they don't have 100% of the factual truth because they aren't going to make life decisions or business decisions based on this information. Nothing bad will come to them because of not knowing.
It's a new communication skill to learn and it will feel very weird for a good while.
Make answers short and memorable and comforting yet non specific. Don't sit around him long enough for him to question you further too much. If you go see him have someone with you to interrupt and change the subject if needed, in 5 minutes he most likely will forget he even asked some question anyway.