My goodness! This almost parallels my situation.
My father past away five years ago. Several months later my mother decided to have her personal affairs taken care for. I found an attorney which drew up a will, living will and had her home transfered to my name and my brother's. She still remains in the house and she will stay until she needs nursing home care. My brother came home from Iraq during the Christmas holidays and started a lot of trouble at home. Mainly, he wanted me out and to have the home to himself. The problem is he can't legally own 100% of the home unless one of us buys the other out. My mother has sided with my brother and believes a lot of the garbage he is saying. I think you may want to speak to an attorney about your rights and what you think your brother is trying to do.
I understand your pain. My mother has totally gone against me and thinks that I am an enemy. It's very hurtful. I have contacted my pastor and spoke to a few therapists to get her help. She was diagnosed with depression several years ago when she had her knees replaced and she seems to be getting worse over time. Her instability has been getting workse especially with my brother back home. Your mother is doing what my mother is doing...finding a replacement husband. You may ask your pastor or priest to talk with her. Let her know that her daughters love her and want only help. Sounds like she may need antidepression meds...but I'm not a doctor. I am trying my best to have my mother evaluated. I know once she gets on meds in two weeks she'll see things a little rosier. But, the tough part is getting to see a doctor about the depression.
I'm so sorry to hear about your brother's behavior. I'm pretty shocked with mine. I really don't think either one of them can possibly feel proud of themselves.