I'm just going to go out on a lonely limb here and suggest that revenge is not a healthy way to respond to a relationship gone bad, and that domestic violence is not acceptable, even if perpetrated by a woman.
Not that cheating on your S.O. is okay, but actually breaking a bone in somebody else's body is way worse, and is justly not tolerated when done by a man, to a woman.
Of course, OP is just stigmatizing her son for being the victim of domestic violence. Suggesting it makes him less of a man because his girlfriend attacked him isn't helping address the issue at all. This is the kind of shit all the MRA types ought to care about: how stupid attitudes about the "right" way to be a boy literally kill people.
Also, having seen just a bit of divorce law in person, let me say that any kind of vengefulness in breakups a) makes you look like at least as big an asshole as the person who wronged you, b) guarantees that everybody concerned will have a really hard time just getting on with their lives, and c) might cost you a lot more than it could possibly be worth. So don't hit him, hit him up, or superglue his dick. Just accept that he wasn't what you thought he was, that love hurts, and get on with your life.
At least he didn't beat you, right?
