If anyone has appeased his anger, he has already suppressed the memory of insults, while as long as the mother is alive the son persists. In order to appease anger, love is necessary.
Remembrance of Jesus’ passion will heal your soul of resentment, by making it ashamed of itself when it remembers the patience of the Lord.
Some people have wearied themselves and suffered for a long time in order to extract forgiveness. By far the best course, however, is to forget the offences, since the Lord says, ‘Forgive at once and you will be forgiven in generous measure.’ (cf. Luke 6:37-38)
Forgetting offences is a sign of sincere repentance. If you keep the memory of them, you may believe you have repented, but, you are like someone running in his sleep.
Let no one consider it a minor defect, this darkness that often clouds the eyes even of spiritual people. St. John Climacus
From the July 16th entry in Drinking from the Hidden Fountain, A Patristic Breviary by Thomas Spidlik, Cistercian Publications