I am not sure if there is anything you can do in that case besides just what you did, answer every nonsensical accusation with the facts. She was not in line, so no one was cutting her. Skin color had nothing to do with it. Gutter-minded people like those you encountered live to set others up.
I think you did well by not sinking to their level. I imagine that they would have liked a dirty brawl and you deprived them of it. Probably left them a little unsatisfied.
There were likely others around who were on your side, but not willing to say so. I dont know why it is that people remain silent and let someone fight such a battle without support. If I had been there, I would have taken your side. I cant stand injustice.
Thanks for your comments.