It takes a lot of work to not care what other people think about you.
There are books and blogs and seminars and programs all with the same purpose: to reclaim that satisfaction, that wholeness that we are born with. It gets slowly drained from us drop by drop until we lose all meaning of what it is to be alone, to be content sitting atop this ball of rock and air and water hurdling through space in a split second of existence.
We are not born with envy, jealousy, or a desire for revenge. Those are instilled in us over seconds, minutes, hours, days, years.
If you want to use revenge as your motivation to not care what others thing, so be it. Just remember that we're born not giving a fuck, and most of us will die not giving a fuck. Chances are, the one thing we'll give a fuck about is whether or not we lived as well as we could have.