Hello Wendy,
I fell in the house a few years ago and smashed my hip. I came out of hospital only a couple of days after my full hip replacement operation (too long a story to explain why). I was fairly young (59) and fairly fit running around as a teacher in a large school, but quite honestly I was totally helpless for several weeks and up many nights in pain for quite a while as I just couldn't lie down properly.
I did all the excercises and was determined to get back mobility as quickly as I could, but I cannot stress enough that the first 6 weeks I needed some one to help me. Ken was in the early stages of dementia then and didn't need me to dress, wash, shave etc.
From what you have posted I would honestly think that you will need at least 6 weeks and perhaps longer bhefore you would be helping him as much as you are now. Believe me it will take you all the strength, time and energy you have to take care of yourself for at least 4/6 weeks after the op. Just getting a pair of knickers on yourself will be hell for a few weeks!
xxTinaT