Karma decides what lessons you need for your next life - whatever form of cosmic justice you are hoping for in this life is not karma. That is not to say that cosmic justice does not sometimes step in - just don't count on every asshole getting the punishment they deserve. Sometimes bad people get to live happily ever after, and sometimes the good folk get punished for their good behaviour.
As for vengeance - whichever version you choose - be true to yourself and to those around you; be true to your beliefs and your convictions; and most of all, don't let other people make you into something you don't want to be. You be the judge of how you apply whatever you find to be justice.
Being a Pagan Christian
My beliefs are ..,
“ AVENGE is better than REVENGE...
What you give is what you get returned. “
I believe you can't appreciate real love until you've been burned.
I believe you don't know what you've got until you have to say goodbye.
But the struggles make you stronger and the changes make you wise and happiness has its own way of taking its sweet time.
Life isn't always beautiful, but it's a beautiful ride.
Dave Tse