Hurt and murder

A 37-year-old Belgian man, Gunter Uwents, admitted that he stabbed his teacher, Maria Verlinden (59 years) 101 times. It was revenge for a humiliation from her during his primary school, when he was seven. a child about 30 years ago. (NDTV news 17 March 2022) Interestingly he used to feed the homeless regularly and claimed to be an active member of a church.
1) Anger: It is possible for children to get angry. However, his anger did not disappear for several years. Paul writes not to let the sun go down upon your anger. (Ephesians 4:26) In other words when the sun sets, anger also should disappear.
2) Suppression: The boy could not express his anger to the teacher or to his parents.
3) Resentment: As a boy, he brooded over the words that kindled his anger. That slowly became resentment against the teacher.
4) Bitterness: The boy was overcome by bitterness. Memory of the incident tortured his emotions that he became bitter and bitter.
5) Unforgiveness: He was not able to forgive his teacher the offender, though he became a born-again Christian. In the Parable of Unforgiving Servant, the king forgave his debt that was ten thousand talents (about Rs. 60 million or 6 crore). However, that servant could not forgive a fellow servant who vowed him just one hundred denarii (about Rs. 50000). (Matthew 18:21-35) Gunter Uwent could not forgive the teacher Maria, though God had forgiven him.
6) Revenge: He could neither forget nor forgive. Hence, his only option was revenge after thirty long years.
7) Violence and murder: Gunter went to her home. He took a kitchen knife and stabbed her 101 times. Did he count his stab attacks?
The school batch mates, and other teachers do not remember any such thing that was done to hurt Gunter. Though being a Christian, did not know the biblical truths of forgiving others, loving others, not being angry with others or Ten Commandments that forbid murder. He was a prisoner of hurt instead of being Free in Christ.
Am I free in Christ?