OP, meant kindly but the other driver was responsible for crashing into you. You are responsible for not seeming to be willing to address your mental state.
You are absolutely catastrophising, you are wallowing in it.....don't make this a "thing".
8 years (ISH) ago, someone smashed into me at a roundabout, the impact was so severe that it shifted me into the car in front of me and wrote off my car completely. I had to have physio for weeks, I had just dropped off my baby twins at nursery so I was very grateful they weren't in the car.
I carried on with life.
18 months ago someone pulled out of a junction into the side of my car and wrote my car off. Again. My children weren't in the car and for that I was grateful. No physio needed.
I carried on with life.
I might be involved in another accident at some point. That's just life.
Not driving doesn't mean anything, you could step out in front of a bus tomorrow, you could get trampled by a herd of cows!
Get some therapy, see if the insurance will pay for it, or does your employer have an employee assistance program?
But don't just settle into your fear- it will paralyse you!