Anne, I’m not a therapist nor a doctor nor any other kind of medical professional, so take everything I say with a grain of salt.
That said, my suspicion is that other people on the road are probably not in as much danger as you think. Per my article, I had a period of time where I was suffering from severe panic regularly, but interestingly, during actual emergencies, I didn’t suffer panic attacks. On some level, my brain knew when I had the ‘freedom’ to panic or not. (If this doesn’t sound like you, well, ignore everything I say 😬)
So, if I were you, I’d start expanding my comfort zone by finding situations I can drive in that don’t make me panic, but do push my comfort zone. Perhaps driving at 50mph down a country road for fifteen minutes, with one other trusted person in the car or alone, would be a good start.