I'm with you stuckinarut. This is the one thing that messes with me pretty bad after leaving the cult two years ago. As someone else said, I'm not afraid of being dead, as I've been there before I was alive. I believe that may be a Twain quote. I don't look forward to the pain or even the medical issues that will one day come. I hate doctors and am squeamish.
When I go to bed at night I am often plagued in the silence by thoughts of death. It is one way where the cult really messed me up. Again, what gets to me is not the fear of being dead, I just don't want to have to say goodbye one day. I don't want to say goodbye to my wife, that crushes me, whether it be myself or her that goes out first. I don't want to have to see her go through pain either. I truly bought the cult's promise hood, line, and sinker. I was promised permanence and I expected it. Now that I'm out I realize that everything points to impermanence from the seasons to the breakdown of everything around me. I like that the Buddhists seem to teach impermanence on the whole.
So yeah, I struggle a lot with this. It honestly dominates me more than I would like to admit. When I was a kid my grandpa told me that we were going to the circus and that we'd have a ball. When he showed up without a ball I was devastated. So I always had a tendency to really buy in and take things word literal. Obviously not so much now, but my whole worldview was based around that filthy cult's teachings. It's in my head and the death thing is the one thing I can't seem to shake. Turning 40 a few months back didn't help, and I've only been out of the cult for 2 years now. I'm sure that I'll figure out some way to accept it better later, but this bothers me more than anything since I've left.