Have the people played different roles in this group? For example, was one the leader who started to hurt you and perhaps encouraged others to join? If so, you probably should forgive one at a time. I would recommend that you rate the degree of hurt that each person gave to you and start with the one who hurt you the least. Once you think you have completed the forgiveness process with that person, move up the list to the next person. Eventually, you will reach the one who has hurt you the most and you will be well-practiced in the process of forgiveness.
Learn more at How to Forgive.