I personally do not fear non existence, instead I only fear life itself and the method failing. The thought of no longer existing is very comforting to me as I know that nothing can hurt me then. In comparison to death, my life seems so temporary, insignificant and meaningless.
I guess that many people fear death as this existence is all they know and after all, humans are programmed to survive, they cannot comprehend what it is like to not exist. I do look forward to death, only I wish that it is easier to actually get there. It hurts me that suicide is this difficult.
I wish you relief from suffering in whatever you decide to do, and I hope that you find what you are looking for.