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.
I am sooo sorry to hear that, Nicole, I really am! :( May God bless you! I just wanted to come out and say that don't feel alone, we here are always going to be there for you! If there is anything I can do to consolidate, just ask! :) It is all natural to be fearful of death, especially after all that you have been through!
It's understandable for people to deal with thanatophobia at some point in their life. You're definitely not alone in this. I've went through that as well and I still do at times. I have lost a few people which made me more aware of death. The idea of death is still a bit scary. You definitely shouldn't feel alone with this. More people go through this than you think. If you ever want to talk about it, you can always message me.