how to react against unfair words spoken to me?

There is no lack of critics in the world. Whatever you do or say, some will speak ill of you, some will say good of you and some will pay no notice to you.

Well, we don't want to hear anything bad about us. So if someone criticize us, so surely we have a reaction of anger or dislike that often comes out in the form of protest and shout. But the reaction should not be like that. In Brahma Net discourse (Collection of long discourses, Sutta Pitaka, Tipitaka), the Buddha said,

         "Monks, if anyone should speak in disparagement of me, of the Dhamma or of the Sangha, you should not be angry, resentful or upset on that account. If you were to be angry or displeased at such disparagement, that would only be a hindrance to you. For if others disparage me, the Dhamma or the Sangha, and you are angry or displeased, can you recognize whether what they say is right or not?" ‘No, Lord.’ "If others disparage me, the Dhamma or the Sangha, then you must explain what is incorrect as being incorrect", saying: ‘That is incorrect, that is false, that is not our way, that is not found among us.’ "

Thus what we should say in response to a reproach is to stay calm, analyzing whether they are saying it as true or not, and then explaining to them about the matter.