I don't know, but I just feel you did right by not apologizing. She had no right to yell at(especially to the glare of the whole school) or use derogatory terms on you. It's said that silence is golden but not in some situations. We both know how things would play if you hadn't come to her level.
One thing too is that, she should have been queried. That was no civil behaviour. And here I thought that staff tried to portray the general school in a good light especially when external officials were present.