What do you think of girls who tell everyone about you? what would you do if they did?

i mean this in a negative way. say that you had talked to a girl for a relatively long time and you two had clicked but there was one problem bigger than the others...her. she didnt know what she wanted but she knew that she needed to have you around in case the guy(s) she likes more than you just werent interested in her. you suspect this because you know that when you talk to this girl, she was your no.1 at that moment, not your backup plan. then when she realizes that you are about to know you are her backup plan (i dont know about you but to me thats just showing no respect) everything falls apart and she just tells everyone. now everyone in your cl knows this from her point of view and you havent said a word. should you stay quiet? is it embaring anyway regardless of what you do that a girl is slandering you?