Matthew 18:15-17, "Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. And if he shall neglect to hear them, tell it to the church: but if he neglect to hear the church, let him be unto thee as a heathen man and a publican."
There are many verses on the importance of forgiveness, but somewhere along the way people got it in their head that they should always instantly forgive, no matter what. But God did not put that heavy of a burden on us. He does not expect us to be superhuman. There are times when you have the right to feel wronged by someone. That does not mean that you hate them, want to harm them, and are going to "pay them back," but it also doesn't mean that you have to just forgive someone on the spot, especially to someone who does not care that they have wronged you or does not realize it. Although, you should try to forgive. One shouldn't have to suddenly forgive the person who has wronged them, but try over time to forgive them, and pray for them.
God's forgiveness is a wonderful thing. And God's Word shows us that we are to give people the opportunity to repent; "Today if ye will hear his voice, Harden not your heart" (Psa 95:7-10), so that we can forgive them and mend the relationship. We are not to hold a grudge, and we are not to have the attitude of, "I will just forgive and forget." You should forgive, or strive to forgive; but depending on the circumstance, that may take time, sometimes a long time. You also won't forget, you shouldn't forget. It doesn't work like that. That pain is real, and will always be with you. To just push that behind you shows that you didn't learn anything from it. That it hasn't taught you, or helped you to grow. Instead offer the pain up for the person who has harmed you.