Douglas Wilson offers some wisdom on the effect of resentment: If you are bitter, you are siding against yourself with the person you're offended at. Wilson writes:
What this means is that someone came into your home and smashed your precious things. And let us say that you are not imagining it—he really did this. And so what does bitterness do? Bitterness goes to the workroom in the basement, finds a hammer, and goes through the house, smashing any of the remaining precious things that the other may have missed. At the basic heart level, this means that bitterness agrees with the vandal. For all the appearance of conflict, it is a false conflict.
Aggressive belligerence says that you should be hurt. And bitterness responds by saying, "No, I need to be hurt and damaged more than that. Leave me now—I can do the rest by myself."