Pray. Ask God to help you forgive. As this is a hard thing to do, it is understandable that you want to forgive but can't find forgiveness. Spend a little bit of time--it doesn't even need to be a long time--but stop what you're doing, spend a little bit of time praying, asking God to help you find forgiveness. And you will find forgiveness some day. It could be years from now, or it could be tomorrow.