I feel sorry for your husband for having suffered from a illness which has not yet been defeated by the medical sciences. I understand that he is quite old (75 yrs)and also had to be hospitalized for his dementia
and is living in an assisted living facility. He will most probably live for around 8-10 years but then he is a human and these things cannot be exactly predicted. The course of illness will also differ depending on whether he takes proper medications or not. As the days progress , he will require more of help and support. Meanwhile, you have to take care of yourself too and should seek psychological help cause taking care of a person of dementia is very very taxing.
Hope I am able to answer your concerns.