I know they’ve already been said, but I have to heartily second You Oughtta Know (which made me scream along and cry when I heard it on the radio right after a really bad breakup) and Song for the Dumped (which I love three times as much since I got to rock out to it live with five hundred adoring Ben Folds fans). Hard-rocking ones are the best for working out pent-up rage, and I much prefer them to sad ones.
No one’s mentioned Best I Ever Had by Vertical Horizon, speaking of sad ones. That also made me cry after my bad breakup. Still makes me cry today, actually. There’s something so yearning and sad about it…