I just came across two opposite quotes. One is from Mahatma Gandhi (Bapu) and the other is from Mahabharat, the epic.

I wonder what a person should do in this situations.
They said,

"An eye for an eye will make the whole world go blind." -Mahatma Gandhi

AND

"Revenge is the purest emotion." -Mahabharat

Obviously, Bapu was a follower of non-violence and peace. He has read Ramayana in his childhood. But Mahabharat is a bit political. But revenge does not mean violence. I respect Bapu a lot.

Revenge becomes necessary at one stage for a person.
Although, Lord Krishna considered revenge as the purest emotion, just to defeat the evils. But today the whole world consider revenge as the violence.
I would propose a person should go according to the conditions and should take the revenge by not being violent. Always remember You have the greatest weapon that is your brain, mind and control.
Control yourself and take the revenge.