<human>: Can you provide a brief overview of the text?

I'm a 25 year old atheist and at a few points in my life I've been COMPLETELY overwhelmed by thoughts of mortality. 

The first time I can remember was when I was 12, and it was about my parents. I became fixated on the idea that someday they would cease to exist, and I would break into tears out of nowhere. 

10 years later, after graduating from University, it set in again. I spent a few weeks unable to get anything done, moping around in a state of depression. This time I was more fixated on my own death, and the death of my fiance. How they would be timed. Would she have to live without me? Would I have to live without her? 

And now... a few years later... it's happening again. 

I don't feel like I'm wasting my life or anything. I've traveled, and plan to continue. I've accomplished some things I'm genuinely proud of and have a life I'm very satisfied with. I am currently hunting for work and the last time it happened I was at a similar transitional phase, so that might be part of it. But I just can't get over the fact that we only have this short little run... and then *POOF*... back to nothingness. 

I honestly WISH I could believe in ANY religious dogma, but none of them seem logical to me. My fiance isn't religious, but she believes we exist as energy after we die. I try to avoid talking about it with her because I don't want to 'convince' her of my much less optimistic view. 

The only possibility I can entertain that slightly quells my fears is that perhaps at the end of our lives we 'relive' our memories for as long as we need to. The whole 'life flashing before your eyes' thing... but even that seems far fetched. 

Am I the only one who stresses about this? How do fellow Atheists deal with such a finite existence? Has anyone been completely overwhelmed by this before? 

Help me out!
<bot>: I get depressed when i think about the fact that there is no afterlife, but no religions or spiritual beliefs offer believable alternatives. What can I do?!?!