If your enemy is hungry, give him food to eat; if he is thirsty, give him water to drink. In doing this, you will heap burning coals on his head, and the Lord will reward you. Proverbs 25:21-22

Here within these verses are the only revenge allowed a Christian; to do good to those who have treated us badly. It doesn't sound like there would be much satisfaction in this, but I can assure you, there is and you will not have to fear God's Reaction. I have used this method of repaying good for evil, and it works. I had a sense of satisfaction while staying within the boundries of God's Expectations. But personal satisfaction is not the only thing that happens. A person who is treated in this manner may repent of their actions toward you. They cannot figure out why another human would repay good for evil. They may even have a curiosity of where this came from. This can open their eyes to the Lord. This can melt a heart long hardened with anger and strife.
I have heard on more than one occasion, God calling a Christian parent to forgive the murderer of their child. This has changed the heart of the offender to the point that they have turned to the Lord. In one case, a close friendship rose out of what seemed to be the ashes of life.
Is it easy to forgive a person who has wronged you? Is it natural to want to do good to them? No. But we do not live by natural means, we live by the Supernatural. By beginning to act on what God asks of us, the Power of God is set into action. If you are in a position where you are being treated wrongly by another, try this. It may change someone else's life for the Lord.