Yes, I have challenges like that myself. We are designed to be more hyper vigilant when something bad happens, we have had to be that way in order to thrive. It is these "fears" that have inspired us to find ways to prevent and this has lead to our developing so many things to protect ourselves and make us safer.
In our history life was a lot more fragile, losing a child was a lot more common and there were many people who were lucky to have a child survive to adulthood. I don't how they managed back then, often a mother suffered through losing more than one child, a woman had to really worry about childbirth too as many women did not survive it.
I understand your fears, but, the only way you can move forward is to work at it and get yourself to a point where you can drive again. It's hard to work through these challenges, I know, I have them myself. I think that you should try driving a little at a time again, I don't know if a long drive is such a good idea, yet, it may be that you learn that you "can" actually do it again just like you finally regained comfort in not having to constantly check on your children and you could finally be ok again.
I have just decided to take it one day at a time now, and as I do that I am slowly working on deciding on accepting that life is just going to happen and all I can do is my best to live it one day at a time.
Welcome to PC by the way and welcome to the PTSD forum.
((Hugs))
OE