My mid life crisis came at 20

This one's going to be very short, talking about the subject that I'm about to bring up makes my skin crawl, and makes me really panic more than anything else in my life.

I can not put an exact date on it but when I was about twenty I realized I was going to do die someday.
I realized I would no longer exist.
A friend told me not to worry, since I wouldn't be around to know what not existing was like.
I just can not get it out of my mind.
I can not handle non-existence or the thought of it.
Even writing this now my heart races and my skin crawls.
Nothing helps. I think about living a long prosperous well to do life.
But the thought of my own demise makes me stress so hard I feel the urge to vomit, and my hands shake.

I wanted to put this down to paper to see if it helps. I am not suprised that it does not. It's going to be a long night...

/s/
Sarx