To be honest, I would be pretty sarcastic/pissed off if my older sister was for all intents and purposes a promiscuous woman. I mean, she probably is mad at her sister for being taken advantage of and willingly letting them get away with it all the while living like a husk of a person. Again, what she said is really rude, but, I'd like to give her sister the benefit of the doubt for now and hope it's because she's tired of her sister's way of life. Regardless of if she has the right to pass judgement or not, she is family, and in real life, if it were my sister, I'd be pretty ticked off by this point.