Here's the problem, really, with unforgiveness. When we refuse to forgive, when we cling to resentment, we are really "dividing the world" - or, at least, our world:
Jesus really did say that we are to love our enemies and to pray for and do good to those who persecute us. Yes, it's hard. Yes, we fail over and over. And, still, as Christians, we are called to love them no matter how many times we try and fail. Perhaps even that repeated failure will bring us to the humility needed to hold both "the good guys and the bad guys" together in our souls.
Don't waste any time dividing the world into good guys and the bad guys. Hold them both together in your own soul — where they are anyway — and you will have held together the whole world.