The practice of courtesy requires you to be a patient and thoughtful person even when someone is discourteous to you.  Practicing courtesy makes you a better person—more considerate, kinder, and more respectful.  Courtesy involves having respect for yourself as well as others.  You’ll be pleasantly surprised at how much more relaxed and happier you are when you practice courtesy under these circumstances.

Anger is only a letter away from danger.  Control your anger because anger will cause you to lose your control and focus.  You want to fight smarter not harder.

If we all insist on "an eye for an eye," soon the whole world will be blind. Gandhi

You are worth defending.  While an instinct to avoid causing pain is admirable, and the necessity of doing so is ideal, there are times when an attacker is just not going to listen to reason.