Anger is a response to trespass. It’s a response to an incident that you feel violates some boundary or value that you hold. When you feel hurt, when you feel wronged, when you’ve been disrespected or humiliated or shamed, it’s easy to hold on to that anger. Sometimes for a long, long time.
I want to suggest that you don’t.
I had some Great Aunts who, well into their 70’s, would occasionally bring up some incident or other involving one of the sisters. They were still angry about whatever the transgression was, still pushed out of shape by it, still holding onto a grudge from something that happened more than 50 years earlier!