We live in a very broken world! We are irreparably damaged and broken! Some of us contain the damage so it's less obvious but no less real!
Part of that brokenness is the damage sinners do to one another. Sometimes that damage is irreversible and beyond repair!
The only response for a believer whose heart has been changed by the love of Jesus is forgiveness! That's tough - sometimes so painful as to be beyond bearing BUT no less encumbant upon our hearts per God's requirement.
Forgiveness always comes at a cost to the one granting the forgiveness.
I'm preaching to my own heart here: When forgiveness is almost beyond bearing to grant, we must - if not for the sake of the one who has done such desperate damage - we MUST forgive for the sake of the One who died that we might be forgiven!