Forgiveness is often conflated with absolving accountability. They are not one and the same. St. Augustine is said to have described forgiveness this way. “Unforgiveness is like swallowing poison and expecting the other person to die.” Forgiveness does not absolve the other person, rather it absolves us from having to hold onto anger, shame, guilt or any other self-destructive emotion. Forgiveness requires nothing from the other person. It is a gift that we bestow upon ourselves. How we deal with the other person is affected by our forgiveness, though, because we can approach them with greater objectivity and better determine how to proceed with them.
So what about Jesus’ utterance on the cross? Firstly, as I have read it, he is asking God to forgive his murdeters. He does not say, “ I forgive you.” I’m sure that there may be many different interpretations of this by theologians, starting with the fact that we don’t really know that such words were ever spoken. My take on it is that if we hold onto our grievances, even to our death, all we have done is live in perpetual suffering. Perhaps the message for the religious is that God will free us of our suffering after our death. I prefer to try to accomplish this during my life. As you shared with your experience, it’s not easy, and using the help of a therapist to let go of anger is a very proactive approach. We probably shouldn’t count on divine intervention.