Yeah, you're dealing with a tough crowd here.
The point they're trying to make goes to precisely the most infuriating thing about this type of female behavior -- they do it precisely because they know full well you can't respond to it in any effective way.
First, you can't hit them, because (male) society has decided, beneficially but to the unilateral handicapping of men, that physical force against women isn't socially acceptable. And you can't apply any non-physical leverage, because you don't have any.
Women are allowed (encouraged) to whine about their hurt feelings or the insensitive behavior of men. It's socially sanctioned and gets sympathy from men and women alike. Men simply are not socially rewarded when they complain about insensitive female behavior -- it's seen as either weak, or overly-demanding, or just plain pathetic. If you make a point of seeking her out for a showdown about something that (at least as far as she's concerned) is "all over and done with," you may even find yourself branded an obsessive stalker ex-.
Put differently, as a general matter, women always get to write the history of relationships (both as the world will view them, and as they themselves view them), and are far better at spinning events in their favor than you could ever hope to be. While you've been stewing silently over this instance of disrespect, she's been busily telling all her girlfriends, and herself, a very different version of the story in which you're the bad loser guy and what she did was not only not wrong, but her only available response. She's got a lot invested in that fictitious history, of which her flaking out is only a minor, and justified, part, and is not going to change a version of events that she and the world have already decided will be the official one, just because you point out that her actions (which she's already distorted in her version to the point where you could probably not recognize them) were socially unacceptable.
Yeah, everyone and I mean everyone recognizes the burning urge to tell a girl who's just done something completely unacceptable that it is unacceptable and that actions have consequences. Only problem is that reasonably attractive girls don't really believe that actions have consequences, and the fact that they're able to do stuff like this without paying any immediate penalty (odds on, she's already happily being courted, or more, by at least one guy) means that they are not entirely irrational to ignore your "message" about how unacceptable their behavior is (although we all agree that it is selfish and morally bankrupt on their part).
