It's difficult, but cruelty should at most times be met with kindness. Unless, the response is to teach that person a lesson in a legitimate sense, then it's okay. But otherwise, if you return the act of cruelty, then it'll just come back around once again. It doesn't help anybody, certainly not yourself.
It is hard to meet cruelty with kindness and sometimes it just can not be done for various personal reasons. However, whenever we can do that, it is good for us for then we do not become like the cruel person. This was a lesson that Nelson Mandela in South Africa personified.
I believe that cruelty should be met with kindness. When someone is cruel to you and you respond in kind, you allow him to degrade you. If you stick to your principles and refuse to sink to his level, you deny him any real victory over you. Although his cruelty hurts temporarily, you have the satisfaction of knowing that you did the right thing. And your kindness and dignity might make an impression on the cruel person and mitigate his behavior in the future, so you might save someone else from cruelty in the future, or even help to redeem your abuser.
Cruelty should be met with kindness only in the correct context and circumstance. For instance, a animal that was treated badly and with cruelty should be treated with kindness. However, the person that performed the cruel act should not be treated in the same way. So yes, cruelty should be met with kindness to counter the negative adverse effects of the situation.
If any disease, in this case wrong / cruel behaviour by a human being is tolerated by others and he/she is given kind treatment; then the cruel person will take the world for granted. Also there is a risk that many people will start believing that they can easily get away with any act of cruelty.
'Some one said, "What do you say concerning the principle that injury should be recompensed with kindness?" The Master said, "With what then will you recompense kindness? Recompense injury with justice, and recompense kindness with kindness."' (Analects 14.34) Besides, a gentleman should hate the wrongful acts of others. 'The Master said, "It is only the (truly) virtuous man, who can love, or who can hate, others."' (Analects 4.3)
Im a firm believer in an eye for an eye. In nature hostility between equal creatures results usually in both showing anger. In our world we show this example in prisons with the death penalty which is usually how we in society see cruel acts against others be dealt with. A cruel act of murder is met with a cruel act of removing freedom and quick fated death.
I personally think that cruelty would not be met with kindness because an individual must give respect to get respect which is a give and take. I personally think that cruelty would not be met with kindness because someone that is being nice to a person that is just being cruel is unfair to the person that is being kind.