Well done Crankarm. You did the right thing.
I also feel that the driver, verbally abusing an injured person laying in the road, is inexcusable. Ok, it may partly be down to human nature and our culture, but thats no excuse. I think a few people calling her names on a forum she probably will never read, is justified.
If it is down to human nature (and of course, she may just have been a very unpleasant person, rather than acting on some primeval instinct) then it's a sort of excuse, because we are a very complicated animal, with all sorts of hidden factors we're unaware of, which only come out at times of stress and so on. That woman may just have been very bad at overcoming her initial instinct. Of course that might be because she's never bothered to try.
More Off Topic: I watched a programme last week about the Japanese tsunami, as seen through home video. A man was filming from a high vantage point, watching dock workers as they first watched the wave coming and then ran away, but only at a jog, looking back all the time. He was saying (it was subtitled) "oh, you idiots, you idiots". Now, even allowing for subtleties of translation, and whether 'idiot' might have a slightly different meaning in Japanese, that seems pretty heartless, since the guys clearly got washed away. But that chap was in a moment of supreme stress, and probably not thinking very clearly.
The real test of the driver, I feel, like someone said above, is how they behave in the cold light of day. She may turn out to still be a heartless cow, in which case, she deserves everything the law can throw at her, plus as much litigation as the victim can muster. If she realises how bad her mistake was, and how bad her behaviour was, and is suitably contrite, then she might just deserve some forgiveness...