Without going into the details of my parent's separation (suffice to say my father is emotionally and physically abusive) my mother has since changed drastically. I expected that she at 53, would change without having my father around to monitor her actions and control her. What I did not expect was for my mother to start an affair with my brother's 19 year old best friend. My brother is in the army and when he's home his friends come to visit. Except my mother started to invite them over when he wasn't around as well. She would always tell me to go somewhere else (which was suspicious) and started to lie about where she was, who was coming over and she would become irate when I asked that these children leave. She told me that I was like my father (ie controlling) and that nothing was going on. The boys just needed a friend and saw her as a mother figure. Then I found her diary which outlined her actively trying to seduce my brother's best friend, her sleeping with him and writing that he is all she has ever cared about. I have financially supported my mother; been there emotionally and tried to help her with the fallout of divorce. She has told me that she hates me and accused me of destroying her sense of privacy (as I read her diary).

I never wanted my brother to find out. I told him when the subject best friend asked him to hang out as though nothing was going on. My brother was willing to let things go as I had told him that my mother couldn't possibly still be doing it. I WAS WRONG. My mother called him yesterday and said that she was 'in love with him, couldn't help it' and some other bullsh*t. She lied to my face and said that there was nothing going on and never had been just two days before. Now she has kicked me out of the house.

What do I do? Should I forgive my mother for her actions and say that it is totally legitimate for a 19 and 53 year old to be seeing each other? Should I accept this new partner? Am I wrong for being disgusted by her actions? My brother wants nothing to do with her now and I am lost. What do I do?