Calmly, I can relate with all you are saying.
I had an "episode" a few years ago where a thought popped into my head-eternity. What does forever mean? There has got to be an end, right? What does forever feel like or what does the end feel like? I couldn't wrap my head around it. That led to, "Why are we here?" You live, work, struggle-some more than others, then die. I finally worked through it somehow, but I was anxious/depressed for a long while.
All those feelings and questions came flooding back as my father was dying. He lived his life caring for my handicapped mother for 52 years. He literally lived his life for her. He had no life other than his job and her. He did EVERYTHing for her, and she is an extremely difficult woman. He was a vegetarian who didn't eat sugar, no salt, and almost no fat. He did everything right, I think, partly in order to be around to take care of my mom. His health fell apart, and he died 2 weeks after going into the hospital. It was unbelieveable!
I could not make sense of any of it. How? Why? All the good he did, and he suffered emotionally and physically in the end. He should still be here. I struggled for a few months.
I try to keep my mind occupied with positive thoughts, but some days I struggle. The bottom line is, we are not going to know what happens until the time comes. I try to remember death happens to everyone; there are those before me, and those that will follow me. We have no control over any of it. I do control how I live, though. I try to do special things for the people I care about. I try to make my husband happy. I have a repsponsibility to be the best I can for my children. Worrying about death and questioning the purpose of life only detracts from the time we do have together. I can adopt that attitude for them, if not for myself.
With that being said, I will check out the Tibetan Book of Living and Dying.