Summarize this article:

Focus on breathing and keeping your cool. Make an active mental effort to calming yourself down. This isn’t always easy, but it prevents you from making a heated mistake and playing into a jerk’s hands. Feelings of resentment and the desire to get even can quickly overthrow your better judgment if you’re not careful.  Breathing helps sooth your autonomic nervous (fight or flight) response and gives you something to fix your mind on other than coming up with something to say or do in retaliation. Draw in a deep breath, hold it to the count of three, then exhale. Do this four or five times. Imagine that the irritation you feel is slipping out with each breath. Pause to mull over what’s going on rather than allowing yourself to be baited. Is the jerk actually saying anything worth listening to? What are you getting worked up over? Once you try to logically account for certain emotional impulses, you’ll find that they quickly fade away. Give yourself thirty seconds to a minute to consider your possible reaction before acting it out. At the end of that time, you’ll probably think better of it. Pull back and stop interacting with the mean person directly. If there are other people around, talk to one of them until you cool down. Otherwise, find something else to focus your attention on to take your mind off an unkind comment or action. If possible, go somewhere else and do something soothing to help you relax. Even if you don't have a way of escaping, you can demonstrate your indifference to the jerk’s antics by directing your attention elsewhere.  Talking to the people around you will also take their attention away from the jerk, meaning they won’t get the conflict that they crave. If all else fails, pull out your phone and pretend to text a friend. That way, you can ignore an antagonist without the need to just sit in uncomfortable silence. You have nothing to prove to mean-spirited critics. Don’t engage them or feel the need to confront them over meaningless words or you’ll just be stooping to their level. Getting defensive is like revealing a chink in your armor that the jerk will zero in on and try to damage further. If they don’t allow them to feel justified in attacking you, they’ll just be hurling empty abuses.  Arguing with a jerk only serves to validate their conduct. There may be times when it’s necessary to speak out against a jerk, like when the person just won’t stop, or when they’re bullying someone else around you. In these cases, try to take a stand without coming off as aggressive. This can just motivate a jerk to push back even harder.

Summary:
Take slow, deep breaths. Think before escalating the situation. Create some space. Don’t feel the need to get defensive.