I believe that it is largely irrelevant what you were doing at the time....the woman in the Ford has to drive in such a manner as to be able to stop, regardless of why she has to, in a safe manner.
In my limited experience the person at the rear has the responsibility to stop, no matter what the vehicle in front does, and regardless of what else is going on in the immediate area.
Your car, engine switched off and doors closed is technically parked....so a static hazard....nothing more.
The question for me is: Why did the old woman stop anyway?
But regardless of her reason for stopping, the Ford woman should have stopped without crashing into her.
I would sleep soundly....
