Before I got divorced in 2016, this was the caption for this drawing: "resentment is a lot like a mosquito bite. The only way to let it heal is to leave it alone." At the time, I hoped that ignoring the problem would make it all go away. I was wrong.
On the left is the before image, which I drew only a few months before we split. I made the changes on the right during the week immediately after, turning the mosquito bite into the necrotized wounds caused by a brown recluse spider. At the time I was just trying to get out my anger, but looking back over a year later I see truth in what I drew.
Resentment doesn't go away on its own. It gets worse. To fix it, you must have the courage to look it in the face and deal with what's looking back at you.