After that, I celebrated each birthday with surprise because each age I hit was one I assumed I wouldn’t reach.

I know exactly this feeling. I often expected the escape from terrible depression would eventually be suicide. I still expect to die by my own hand when my quality of life declines from health problems or old age in the future.

Funny thing is, my father was the same way. He procured for himself whatever drug is administered in right-to-die cases and warned me that he had it a number of years ago. But he never asked for it when he went into hospice due to age-related health issues. He clung to life until it was gone.