The source of resentment is resistance so the anecdote to it is acceptance, and consequently, forgiveness. We perceive that we have been wronged, that someone's behavior is reprehensible and not ok... and yet, we rarely ask ourselves if we have ever done the same given similar circumstances. We can feel disappointed, frustrated, hurt, etc, for the way others behave, but if we are spiritually fit, we must not judge, lest we be judged. We have to remember that when we point a finger at someone, there are three other fingers pointing back at us.
If we want to stop feeling angry and done-to, we have to divvy up some forgiveness. We have to allow others their mistakes and trust them to do the best they can with the information and tools that they have. Let's give them the dignity of self-correction and not harp at them and nag and rifle with blame.
I accept the mistakes of others and do not take them personally or hold a grudge. I am understanding and forgiving.