Let's consider some truths that can help them, and us, move forward from the ledge of bitterness and unforgiveness, and into the peaceful place of forgiveness and acceptance:
First, into each life some rain will fall. Yes, this is a cliché, but we sometimes forget that we are not immune to difficulties. Scripture is filled with stories of adversity, and the importance of preparing for it and in a certain sense, accepting it. The Psalmist cried out for relief from his distress when he said, "Give me relief from my distress; be merciful to me and hear my prayer." (Psalms 4:1)
Second, we are to embrace adversity, watching for the opportunity in it. The Apostle James tells us to "consider it joy when you encounter various trials." (James 1:2) He goes on to tell us that these struggles make us stronger. So, rather than fight against our struggles, we must actually lean into them, embrace them and learn from them.
Third, rarely is the "offense" one-sided. In most challenging situations, rarely is there strictly a perpetrator and victim; one who is absolutely right and the other absolutely wrong. Thinking in this manner is often a major block to moving forward with the forgiveness process. Consider your part in the offense; reflect on your part in the troubling situation. Try to understand the position of the one whom you believe wronged you.
Fourth, forgiveness begins with a decision to forgive. Don't wait until you want to forgive someone. Begin with a conviction and desire to forgive. Allow God to work on your heart to move you forward in the process of forgiving. Believe the Scripture that assure us "He who began a good work in you will carry it on to completion." (Philippians 1:6)
Fifth, even when wronged, we must forgive. This is never optional. While we may never fully forget what occurred, we must let go of the debt we feel owed to us by others. Scripture tells us, "Be gentle and forebearing with one another and, if one has a difference against another; even as the Lord has freely forgiven you, so must you also forgive." (Colossians 3:13)
Finally, remember forgiveness is a process. It takes times to forgive and let go of hurts. There are definable stages of grief, starting with denial, leading to depression and loss, and ending with acceptance. Allow yourself time and understanding as you move through those stages leading to forgiveness.