Could it be that the reason you fear death less as you get older is because you have done more in your life?

Or maybe because you know that certain things, if not done by now will most likely not be done in your life, and so the burden of "things left to do" is lesser as well.

I still fear death in that, like I said, I have many more things to do in life, but I've also known older people, even older than you, that fear death as well for this very same reason so not sure if this would be a potential reason or not, but I find it interesting.

PS. Sorry to hear you are going through a bad time :/