>“Holding onto anger is like drinking poison and expecting the other person to die."
Do you often fantasize about bad things happening to people you dislike, including engaging in revenge fantasies?
This is called "ill-wishing" and is one of the worst forms of black magic - not necessarily for the target (though it can, via the hateful actions of the ill-wisher who can no longer be sated by mental masturbation) but for the practitioner themselves. This illness is very much physical - it feels terrible to hate, and to rage. It needs an outlet, and so to give this poison such you direct it towards fantasy, much like masturbation.
There is a way to dispel anger in a way that is not poisonous. It is the act of well-wishing. In this visualization, you imagine the transgressor in a future period having grown out of and moved beyond whatever caused the transgression, and have become a happier and better person because of it. Remove your own ego from it, such as the expectation of an apology, or specific ideas about what would count as growth.
It is also important not to expect such an outcome to be an occurrence, but instead to acknowledge it as an ought.
This is an emergency measure one can take while they look for better methods of emotional regulation. Mindfulness meditation in particular is great for treating the underlying issue.