I can relate. I'm a few years behind you, but starting to have thoughts similar to yours.
It's not easy to remain positive, even though it makes sense to keep trying.
I can begin to see where the phrase came from, "parting is such sweet sorrow".
I only hope that my wife beats me to it, since I can't stand the thought of her being alone.
People love to say that they have no regrets. But, I believe it's because they either might not want to share their regrets, or don't want to bore anybody with their story. Personally, I'm starting to regret having accumulated so much stuff. It's not easy getting rid of it.
Good luck to you, and to everyone facing a similar juncture.