You're right Marta, wherever you go, you will always meet lousy people, fortunately there are nice people too.
i don't know why some women act like that, maybe some competition, sort of "I'm more attractive than you, look I can take your BF, I have the power" It's very immature and insecure behaviour but there is always hope that this girls change their behaviour when they are grown ups.
Sorry, you had this experience.
hugs
Annette