There is quite an amazing system more or less programmed by our Creator into the human psyche that provides remedies for those who have been guilty of wronging others (which means, all of us).
Either the person you have wronged will forgive you or they will retaliate; in either of which scenario, you are freed from the burden of the wrong you did to them. More often than not, however, if they do not forgive, their retaliation will not be proportionate to the wrong you committed; it will be more severe. In this case, not only have you been freed from your burden, but you are in fact deserving of compensatory reward due to their disproportionate vengeance.
Perhaps the cruellest thing anyone can do to someone who has wronged them is to neither forgive them, nor retaliate at all. This leaves the sin around their neck until Yaum al-Qiyamah. But this is a rare scenario among human beings. Generally we either forgive, or over-punish.