Do you ever think, "I'll never forgive her!"? Do you ever tell yourself that you will never talk to your friend again? You yell at someone and you walk away, angry and betrayed. You resent them for what they did, for what they said. And when you feel that nagging thought in your head telling you "That was harsh" or "Forgive them" you push it away.
But God does not want that. God wants you to forgive.
"Bear with each other and forgive whatever grievances you may have against one another. Forgive as the Lord forgave you." -Colossians 3:13
When you realized you were a sinner and repented from a true heart, God forgave you. He forgave you for every little sin you've done. He set an example, and He wants us to follow it. You mat think, "I can't. What they did was unforgivable." Or, "It hurt so much. How can I possible forgive them?" God did not say that. Instead, Jesus not only took all of your sins from you, He also forgave you for hurting Him.
Being hurt badly is not an excuse to not forgive. No matter what you say or think, you CAN forgive your friend. With God, anything is possible. It may take some time, and you may need a while to heal, but when you ask God, He will help you forgive your friend. ♥