This is something that most of us deal with even when we don't realize it. We feel like we have a right to be upset (we usually do) at somebody who has wronged us. But what I'm finding out in my own life is that being mad at someone effects you a whole lot more than it effects them. They aren't the one going through their day re-hashing what was said or done or thinking of what might be said or happen next.
God really spoke his own words out of my mouth in worship one morning and I totally lost composure. He said "help me to love *insert name here*". when those words came flying out I was unsure what to think. How could I possibly love someone who I feel has done so much to me? And how could I continue to show love to someone who continually expressed hatred to me?
This is when god ultimately started working on me about forgiveness.
I can't tell you I have this all figured out but I can tell you that I have started receiving small glimpses of joy returning back into my own life as I am letting go of my hurt feelings. Once I realized that my joy was not held back because of someone else, that it was me controlling it, I decided to stop blaming and to start fighting back. There are times I wake up at night for no reason and start thinking about all the hurtful things and the situations that are yet to come and I have to set my thoughts captive and tell my mind to shut up in Jesus name. When these attacks come I lose sleep, then in turn have a harder time the next day and it really is just a ripple effect.
Forgiveness is less for the person who you are forgiving, and more for you. Until I learn to fully release forgiveness to the people who I feel "owe me" something I will be held back. Thank god for this revelation!!!