Rom. 12:19 Dear friends, never avenge yourselves. Leave that to God. For it is written, "I will take vengeance; I will repay those who deserve it," says the Lord.
One of the normal things to do as a child is to get even with those who does him wrong. I know I did it. Regardless whether it was a sibling or not, I wanted to make things even. You do me wrong, then I will do you wrong. It was the law of nature. Sadly, many never grow out of their childhood years. They are bent on getting even when they are wronged, often causing much harm, even death. It is a theme that is interwoven throughout the things that entertain us. Avenging ourselves only seems like the right thing to do.
However, God does not see things as we see them. He says to let Him take care of those who wrong us. It is not our role to play God with others. Instead of getting even, we are to strive to just let things go and move forward with grace and love. We are to forgive those who wrong us and strive to live peaceably with them. We are to pray for those who have vengeful hearts instead of making them pay for what they do.
God is just and He will take care of whatever business needs to be taken care of. If vengeance is needed, He will take care of it at the proper time. He alone knows when it is time to execute justice. He does not act on the same timetable that we do. He sees what we don't and knows whether or not the vengeful soul will repent. He gives everyone ample amount of time to change their attitude and actions. He would much rather wait and not have to mete out vengeance than to do it quickly and lose a soul.
When someone wrongs you, don't take matters into your own hands. Instead take them to the Lord and let Him take care of it. He is able and will do the right thing every time.