The fear that you speak of i am sure has haunted us all at one time or another. I think my health anxiety is basically a fear of death. I fear dying while my kids are still very young just like you said your father passed when you were young. What if i don't get to teach my kids everything they need to know etc. etc.
Shit i don't want to die period but one things for certain is we are all going to. I have to just keep plugging along, day after day and do what i must. I truly feel your pain and you are not alone by a long shot.
I will say one thing though, i have wasted a lot of years worrying about it that i wish i had back. Peace to you