Learning to forgive is much more useful than merely picking up a stone and throwing it at the object of one's anger, the more so when the provocation is extreme. For it is under the greatest adversity that there exists the greatest potential for doing good, both for oneself and others.
Grief and tragedy and hatred are only for a time. Goodness, remembrance and love have no end, and the Lord of life holds all who die and all who mourn.
Goodness is to do good to the deserving and love the good and hate the wicked, and not to be eager to inflict punishment or take vengeance, but to be gracious and kindly and forgiving.
That your enemies have been created is God's doing; that they hate you and wish to ruin you is their own doing. What should you say about them in your mind? "Lord be merciful to them, forgive them their sins, put the fear of God in them, change them!" You are loving in them not what they are, but what you would have them to become.
What is tolerance? It is the consequence of humanity. We are all formed of frailty and error; let us pardon reciprocally each other's folly - that is the first law of nature.