Forgiveness, like love, is not a feeling but a decision/a choice.
If you are having trouble making that choice or following through with it AND you recognize that your lack of forgiveness is contrary to God’s Will, may I suggest you bring this to Confession? The graces received in this Sacrament can help you. You may have to confess this sin, and the anger you feel (murder in the heart), a number of times, but healing will come.
The act of examining your conscience will help to identify the problem and it’s roots. Confessing acknowledges it before God and man. Absolution completes the process and allows the grace of this most beautiful Sacrament to flow into your soul, strengthening your resolve to do better.
I’ve been in a similar situation, have done this, and have been able to let go of the whole thing, gaining peace. It was a process that took a few months but I no longer harbor the anger and resentment I once did. The other person and I are not best buddies but I can truly say I have forgiven that person.
Be at peace.
