I think it describes it very well in matt 18:22 -
Then Peter came to Jesus and asked, "Lord, how many times shall I forgive my brother when he sins against me? Up to seven times?" Jesus answered, "I tell you, not seven times, but seventy-seven times.
"Therefore, the kingdom of heaven is like a king who wanted to settle accounts with his servants. As he began the settlement, a man who owed him ten thousand talents was brought to him. Since he was not able to pay, the master ordered that he and his wife and his children and all that he had be sold to repay the debt. "The servant fell on his knees before him. 'Be patient with me,' he begged, 'and I will pay back everything.' The servant's master took pity on him, canceled the debt and let him go.
"But when that servant went out, he found one of his fellow servants who owed him a hundred denarii. He grabbed him and began to choke him. 'Pay back what you owe me!' he demanded. "His fellow servant fell to his knees and begged him, 'Be patient with me, and I will pay you back.' "But he refused. Instead, he went off and had the man thrown into prison until he could pay the debt.
When the other servants saw what had happened, they were greatly distressed and went and told their master everything that had happened. "Then the master called the servant in. 'You wicked servant,' he said, 'I canceled all that debt of yours because you begged me to. Shouldn't you have had mercy on your fellow servant just as I had on you?' In anger his master turned him over to the jailers to be tortured, until he should pay back all he owed.
"This is how my heavenly Father will treat each of you unless you forgive your brother from your heart."
Just because someone has sinned against us more then we have sinned against anyone else, does not mean we have the right to not forgive them. Because our ultimate debt to God is beyond anything we can pay, we have to give up our right to not forgive others. And also because God is the only righteous judge and the only one allowed to have the final word.