Normally, it is good advice:

Give the guy another chance. Try to understand why he is treating you unfairly. Be slow to anger, quick to forgive. Go the extra mile. Let him know you're willing to let bygones be bygones, show him you have no ill feelings, and are willing to try again. Make sure you are not giving offense, or that there is a misunderstanding. Much, if not most, conflict is the result of misunderstanding. Demonstrate your willingness to meet him halfway, or even let him have a slight advantage if he is especially insecure.

But there comes a time when you realize some people mistake kindness for weakness, fairness for cowardice, compassion and reason for effeminacy. And they have only contempt for those qualities we perceive as virtues. And when these people show that they plan to take advantage of your cheek-turning, to use it to humiliate and torture you, you must realize that this is not a misunderstanding or an understandable or inevitable conflict. These people are pathological, and they must be destroyed. Not repelled, or punished, or put in their place, but exterminated. Because if you don't, they will only emerge again, and even if they avoid you out of fear, they will plague someone else instead. You owe it to them, those who have not as yet met this evil; not as a treatment for evil, but as a sterilization against it. And you will give an opportunity to those who intend to strike the other cheek to reflect on what can happen to those who do. Perhaps they will learn.

Turn the other cheek, let him know you are no threat. If he hits you again, smite him, run him through or shoot to kill, without hesitation and with a perfectly clear conscience. It is not only your right to protect yourself, it is your duty to protect others.