You could have 20+ years left of life. What would you like those 20 years to look like? You already have an idea – based on the past 50 years, and definitely the past 10 – what life with your husband will look like. At this point, I’m not sure you’d even need to divorce him to live separate lives. It sounds like you already do this. As for it being unlikely that you could find another sexual partner just because you’re 76, don’t sell yourself short. That’s 50 years of your husband’s influence talking. It might help to work out some of this with a therapist.
You still have time to create a live you want to live.