This is very difficult I must say. Forgiving people or someone who had wronged or hurt you so deeply isn't that easy always but with God it is possible.
"TO ERR IS HUMAN, TO FORGIVE IS DIVINE".
Offences are inevitable.That is, we cannot stay without offending one another but we should learn how to forgive each other.
Jesus didn't only talk about forgiveness, but He also demonstrated it practically.
In spite of everything that was done to Him even to the point of death.
Luke 23:34 ( KJV),
"Then said Jesus, Father, forgive them; for they know not what they do. And they parted his raiment, and cast lots."
Matthew 6:14-15,
14 For if ye forgive men their trespasses, your heavenly Father will also forgive you
15 But if ye forgive not men their trespasses, neither will your Father forgive your trespasses.
Forgiveness is very vital, if you do not forgive your offenders , your heavenly Father will not forgive you too and if you are not forgiven by God, your salvation is not sure and that means there will be no place for you in the kingdom of heaven.
When someone offend you, it is good in the sense that you have the opportunity to forgive, the Father will also find the opportunity to forgive you your sins, so it is for your own good if you forgive.
Matthew 5:7 (KJV),
Blessed are the merciful: for they shall obtain mercy.
If we show mercy God will also show us mercy. God allow people to offend you in order to learn how to forgive so you too will be forgiven by Him.
It is not good that we always remember the bad things that people do to us.