Don't feel alone. Most people will or do, at some point in their life, suffer from thantophobia. I used to have it, but at this point, I don't fear death nearly as much as I used to. Eventually, you can come to terms with it. You may want to look into getting some grief counseling or, at the very least, look at some information about the stages of grief and how to overcome struggles when someone you love dies. My father died just a couple years ago and I used to have so many nightmares about death- I would leave notes everywhere because I was scared I would die, too. You aren't alone, I promise, but with enough research and thoughtfullness about your own mind (perhaps you should keep a journal to keep track of your thoughts), you can overcome this.