eperaltaotero, I have been in situations where ethnic slurs have been directed at my wife. Some may think me a wimp for just ignoring them but frankly it was much harder for me to ignore them than to insult back or become violent. The way my wife and I look at it is that we are not going to let some other person's ignorance dictate our actions unless we have to for reasons of self defense (words can only hurt you as much as you let them, also if you allow yourself to get caught up in the emotions of an argument your ability to asses your situation will be diminished).
On the other hand we were once in a situation where a taxi driver in DC became abusive and actually grabbed my wife's arm restraining her while shouting at her right in her face, unfortunately I had to disorientate him a little. If you can see the aggressor is about to become, or is already being, violent then I think acting in self defense by striking hard and, if possible, striking first is an option that is worth considering. Then make a hasty exit before the aggressor has time to recover.
Bottom line for me is if I can avoid a fight or escalating things then I do my best to do that (I did many years of martial arts when I was younger and this was what my teacher was always saying, it seems to have stuck with me).