How do you guys get over resentment?

I'm wondering because, I'm pretty sure my mom is ESFJ, and I'm concerned about her from time to time, because eventually she gets over it when she's upset, but in the mean time she broods and broods and broods, and talks about the person a lot and what they did to offend her. She's very sensitive to certain things, like if someone does something that implies that she's not a worthy person, and she takes a lot of that to heart; I feel really bad for her. She rarely takes any of my advice, but I guess since I'm her daughter and thus younger and have less life experience I can understand that; she's also used to being the one caring for others, giving advice, etc. so it is challenging for her to be on the receiving end.
I wondered if this is common among ESFJs? And does it usually take you a long time to get over hurt feelings?