God says that you must forgive because you have been forgiven. Period.
Forgiveness does not mean you let them keep hurting you. Forgiveness does not mean accepting abuse. Forgiveness means that you relinquish the expectation that they can fix what they did to you.
When forgiveness is difficult, it helps to remember two things: 1) who you are in Christ and who you might have been but for the grace of God, and 2) Jesus didn’t just die for the people you like and who treat you right — He died for everyone.
Remember that God forgave (and continues to forgive) the worst in you, so you are not above forgiving anyone of anything. As with anything else, faith doesn’t make forgiveness easy but makes it possible.
Above all, forgiveness means that the other person no longer has a stranglehold on your mind and your thoughts. You can let them go and watch the bitterness and unrest in your heart being replaced by peace and joy.
Lord, help me always to choose forgiveness because of how freely you forgave me in Christ Jesus. Amen.