Hi Rachel,
I am sorry for all you are facing right now. I feel reflected on your words, somehow. While I was living overseas, I was the only one that have rapport with my brother, my sister was always fighting on his mental health issues (she passed away in 2010). Now that I am here and see how he behaves on a daily basis (and react in consequence) I became "the evil one". (before it was my sister). My mom did not have a "good"relationship with my brother but recently, when exhausted she gave up. I somehow feel sorry for my brother because he is sick, but cannot help him, I just can't. And, if I could, I would not see him anymore, because he is not good to me