I exploded used some very strong language and told her to get to the back of the queue. Everyone went deathly quite and stared me or the floor.
Are you Polish? Did you explode in Polish or English?
IME criticising people's behavior in public has always been okay in Poland, sort of a national pasttime, but yelling and losing you're temper makes you look like a psycho and that's how you'll be treated.
The thing to do is to say something critical with some semblance of style (or trying for same) or at least in a calm voice.
"Hallo, pani zachowuje się jak bydło." or even the old favorite "Pani pcha jak bydło, czy Pani jest normalna? " would be more effective than screaming.