Jesus teaches us to forgive. Forgiveness is to set a prisoner free and realize that that prisoner is you. No forgiveness can lead to mental disorders. Do not hold anger, bitterness and resentment in your heart. Whatever someone offends you forgive them even if the person is faking his repentance or did not even ask for forgiveness.
Matthew 18:21-22 Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times?
Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven.
Unforgiveness is destructive both to the both to the body and to the heart. Many believers get offended and even leave the church because unforgiveness. When someone offends you, go to the person and talk about it but if you can't, tell someone who can handle it so that it can be dealt with.
Don't go about gossiping with others about an offense done to you when they can't handle it. Forgiveness is not an option, God commanded us to forgive. We forgive people so that our prayers will not be hindered.