If you're going to be so self-righteous and holier-than-thou and hypocritical as to think you're holier than somebody because they have sinned against you, but oh, no, you've never sinned, therefore you're not going to forgive them--then you're the biggest sinner of all!--And if you have self-righteous feelings of being better than they are, and you look down on them like the Pharisee who said, "I thank Thee, O God, that I am not as this man" (Lk.18:9-14), then that holier-than-thou, self-righteous attitude in itself is the worse sin!--In fact, self-righteousness is one of the greatest sins of all!
We should take a kind, loving, sympathetic and forgiving attitude toward others and try to have mercy as we want mercy, and treat others in their errors as we want the Lord to treat US in ours! We must forgive those who've wronged us, and seek forgiveness of those we've wronged, and take them by the hand back into our circle of love, fellowship and joyful labours together.
May we all be more humble, more patient, more loving, more kind, more forgiving and more long-suffering with each other, Lord.--And may we sincerely pray, "Forgive US our sins as we forgive those who sin against us." (Lk.11:4)