Do you have any firm beliefs in an "afterlife"? I think maybe the fear is worse if you don't really know what you believe, or if you can believe in anything.
As for myself, I firmly believe in reincarnation, so I am quite sure I'll be back again...and again...and again....that allows me to be much calmer about the thought of 'dying', because I know that I'll see everyone I love the next time around.
Maybe your fear will be lessened when you discover what you truly believe.
Just my two cents worth...hope it helps!