"How people treat you is their Karma; how you react is yours" - Wayne Dwyer
A lot of the time we react instantly in a negative way without taking the time to think longer because it's a part our defense mechanism to protect ourselves when we are presented with an offensive situation.
That initial "Thump" in the nerves can make us want to reflex instantly against the perpetrator, which is normal, we're all animals at the end of the day.
What we can try and notice though, is the few seconds we have just before the reaction, the few seconds which is the time and the area where we feel the "Thump".
With a few deep breaths while in this zone and a conscious look at how we are going to react can help us choose a different reaction. In time we can expand this space to help us chose not to react, or to react in a different way and as a result we will find satisfaction and happiness which could also diffuse the situation in the end.
Remember the saying "Two wrongs don't make a right"
-Your Life Drive.