I don't think the police came, it looked like security. I think 'help your brother' was because Teresa was saying her brother should be more loyal to blood (her).
I don't blame her for not getting involved in splitting the fight up and running off. Melissa looked her in the eye and asked her to help and she didn't; by the end of the night she had saved the day (had nothing to do with it). I think everyone else was just trying to split them up - except the facilitators.
Melissa was pissy at Caroline coming to help. She has a bee in her bonnet about Joe and Caro having a drink. It's the only glimpse I've seen a sliver of what Teresa complains about.