I don't want to be in the middle between mom and brother?

[Rachel]

You have every right to set boundaries with your mother. Have them use email or facebook each other.

My mom used to use me as a sounding board regarding a brother who came to live at her house "for one year to get out of debt" and stayed for over 7, never paying her any rent and expecting her to give up more and more of her house as he got married and had 3 children. I used to listen and agree that it wasn't cool for him to do this until one day I got tired of it. I told her it was her house and she was the only one who could put her foot down. If she wasn't willing to do anything about it then she was just going to have to put up with it and not come to me any more about it because I couldn't do anything about it. She stopped talking to me about it and I wished I had said something much earlier.