A bad case of bronchitis has sidelined me for a couple of days, so I had a chance to read "Reflections." I think it is a marvelous expression of an inquiring soul-
I was not totally surprised but not any the less distressed when I read the final chapter. Have you had any treatment for your condition? Has it stabilized? Often when such things show up in later life, they become manageable chronic conditions. My uncle lived with cancer for many years after he had been given up for dead by doctors who "removed what they could" on the operating table and closed him back up again. He lived to enjoy many years of fishing and playing golf and cards. And he did not die of the cancer.
As for some of the important questions you raise, I have no easy answers. It may very well be that the experiment called "human civilization" is in the process of coming to an end. Frankly, I don't see how things can just go on indefinitely as they are. Neither science nor the existing religions can provide a sound basis for a truly human society any longer, if they ever could. Bankruptcy looms. As to whether this ending, when and if it comes, would be a "good" or a "bad" thing, I cannot judge. Both, I suppose, from various standpoints. Perhaps what would replace it would bear a stronger resemblance to the naturalistic tribal cultures that were everywhere eradicated and displaced in order to make room for "us".
As to the metaphysical question of whether human personality survives death, I often muse that this is a meaningless tautology. I don't think that we have the slightest clue, really, of what personality or consciousness truly is-
Space is indeed the final frontier for the country of manifest destiny, but it need not be a shallow and vainglorious one, if we can learn to see this path as the outer manifestation of the infinity within. Only time will tell whether this is still possible for us.