My brother's girlfriend and I do not get along at all.

My brother was originally going to ask this girl out, (let's say her name is Jess) but one of his closest friends convinced him that she was using her to get close to him when really Jess just wanted to be friends with (let's say her name is Anna) Anna. My brother cut off all communication with Jess and she quit speech and debate because of my brother and Anna. At a different speech and debate meet, a bunch of my brother's friends said that he and Anna should be together. She was extremely hesitant to saying yes to dating him but he eventually did. Anna is super nice to people up front, but behind your back she will talk about you all she wants, I know because I have spent time with her. Fast forward to today and my brother and I haven't talked for weeks. He drives me to school everyday but I never say anything because I cannot stand talking to him. Everything is about him and how sad and depressed he is and how his life sucks, He used to see a counselor but is good enough at lying that he convinced them that he is fine. Today, his girlfriend walked into a room my friend and I were sitting in and sat right behind us when there were plenty of other seats around the room. We could hear them whispering and laughing at what we assumed was us, so we moved to the other side of the room. She scoffed at us and continued to stare at us for the entire presentation along with her friends. About two hours later we were all sitting in the gym for an end of the day presentation and she happened to be sitting two rows in front of us and just to the left. Her and her friends kept turning around and looking at us then turning around and laugh amongst themselves. I don't care what they say about me but I will not accept it if they bring my friends into it. I told everyone to ignore them and not look over even though we could always see them looking at us. Finally the school day ended and my brother was super mad at me. Anna didn't tell him about today, but he is just mad at me. I believe his girlfriend is what has been pulling us apart and it is tearing our entire family apart becasue the two of us don't communicate anymore. I honestly don't know what to do.