We loss my mother in-law to Lucy to Dementia so I know your pain. We took care of her for 16 years after my father in-law passed from cancer. My in-laws were pure gold so we had no problem stepping up to take care them. When Lucy got bad one thing that really brightened her up was music. She could still remember all the old hymns from when she was a girl and would sing along. I had a portable CD player we kept in her room and we would setup the CD to loop. She would sit for hours and listen it really brightened her day. Perhaps music will bring your wife the same pleasure?
I'm 62 my wife Alice is 65. She suffers from Lupus, Diabetes, and has 4 stents in her heart all in the last couple of years. I worry more about her if I go first. Congestive Heart and Lung failure got my father at 66 and his father died at 52 but that was in 1926. He was a farmer so the chances he ever saw a doctor aren't good.