A little lesson I'm learning

I am having a lot of trouble with forgiveness lately. Not sure what to do with what I've got. I want to say I am forgiving and most times, people need forgiveness and I say, it's already forgiven. Done. But I have been really carrying something around, for the better part of a year. I do not want to let go of it. Plain and simple. I want to hold on to it, and be mad about it. It feels better. In Bible class maybe a month ago, it was discussed how you can handle the situation correctly, just as God wants you to, and it still not feel better to you. I totally identify, b/c it is unsatisfying. Giving in, and forgiving, and letting go is no fun. Accepting what happened and moving on is not nearly as satisfying as sitting there and stewing over it, and using it as a weapon whenever possible. Holding onto what hurts me is so easy. Letting go is near to impossible for me. I didn't used to be this way. This anger and hurt that I am holding onto is a new feeling for me. I could justify it by saying that I have never been hurt this way. True as that may be, it's not an excuse. I know all the rules, and the reasons for them. Forgive 70 times seven. Jesus forgave me for everything I have ever done, or will do. I am so thankful for that, so wouldn't I in turn want to forgive as often as I can to show my Lord I am grateful for His grace? I should.... But it's not an actual act that I can do, it's a changing of my heart. I'm not ready for it. I feel like Paul b/c I want to do what I ought to do, but I don't want to do it! That confusing verse makes sense now. This bitterness I am letting grow inside of me is spilling over and growing, moving into areas that it shouldn't have spread to. That's what happens when you ignore what God asks of you. This ickyness grows, makes a blackness in the heart. I am currently praying to God to help me cleanse my heart, I need his help so badly. At this point I know I can't do it alone, and know that I never really could.