I had exactly this situation happen once. It was really rattling - I was very upset, started to lose all faith in humanity, etc. I agree with the other posters that you were in the right. Some people just have an axe to grind, and you happened to be an easy target for this woman's aggression.
I try to console myself by remembering that if they yell obscenities and/or throw things at me, at least they were paying enough attention to see me on the road.