What is "not right" about this. I am biased as I had to do it with my mother and it was a great decision. My wife was reluctant until she got to know my mother. My mom never abused me. It was the whiney, selfish, victim I didn't need. Do what you know you need to, then deal with the guilt if you have it.
If this was an acquaintance, not your mother, would you put up with it? 45 years- you have done more than your daughterly duty.
Go be free and happy.