A.R.
My mother and father in-law were in a hospital/hospice, respectively before they passed. While knowing it was best for them, it was very difficult, particularly with my father in-law, to know he was in pain or needed something/one and had to wait. Hearing people crying out in pain, because their medication is making the rounds was difficult.
My mother (our circumstances had changed to allow this) lived with us the last 5 years of her life. She could be very critical, and at times said things to one of my children that had me wondering how she could say that.
Yet, with all of that I wouldn't trade our time with her. The gift to my daughters is immeasurable.
The times she was difficult, I took time for myself, went for a drive, called a friend in a similar position to "vent" and receive support. In short, I took care of myself, while taking care of her and when she couldn't/wouldn't accept assistance or suggestions, I let her be. This WAS the hardest -- letting her eat things she shouldn't, letting her stay home even when a neighbor was asking for her company, etc.
It really is similar to how we are with our children. When an older parent wil listen, speak with them. When they are being obstinate, take yourself out of the situation (since it's unlikely that he'll go to a "time out".) Also, at times, it may be helpful to have your husband speak with him rather than you. It may also be helpful to re-negotiate boundaries, schedules, etc. together. You are all re-defining relationships.
Mostly, remember that you are all doing the best you know how. He isn't intentionally, consciously doing anything to "bother" you or upset you. His ways are just different than yours.
Best wishes!