However hard I try to let go, I keep thinking of my childhood bullies, the teachers who did nothing to prevent them and, worst of all, a close friend of mine who went to uni with and became a close friend of one of said bullies, leading me to destroy our relationship.

These feelings simply hurt and nothing more. I fantasize about revenge but have neither the resources or will to genuinely pursue it. What practices, therapy or anything else could help me address this?