Q: How do we know when we are holding on to unforgiveness?
A: By living in the past and continuing to want vengeance. When we want people to pay for something they have done to us is not only playing God but holding on to it. Go to God in prayer and let him take it from you. Choose to forgive them and pray for them. Also I believe in Christian counseling, if you need it then get it because if you don't then you are continuing to let that person harm/rape/molest/abuse/trick/ you. Don't live in yesterday for it is gone but start living in today by choosing to forgive and let Vengeance be God's for he knows what's best. This has helped me so much. I can now live in freedom and know that yesterday is gone and tomorrow may never come but today is a GREAT day!
Be blessed!