Im not sure if what i have to say is advice, but i have been though something similar.My younger brother is extremely abusive he attacked my mom couple months latter he attacked me in front of my kids in a way where i thought he may kill me. i warned his wife after that something not right it more then just mental, it a excuse and im only one in my family that believes it a lie. i told her that this will happen to her in due time. She called me a liar and horrible person for throwing my brother in jail. After that he turn friends i had since high school against me but in less then year he attacked her . So what have done i cut my self off from him and at first it was about anger but there this quote i found “There are two things a person should never be angry at; what they can help, and what they cannot” I cant help my brother i have tried for years and it hurts just yesterday i saw two kids playing outside and it reminded me growing up with him. I just dont need that in my life, ill end this on a light note “Decide you must, how to serve them best. If you leave now, help them you could; but you would destroy all for which they have fought, and suffered.” Yoda. Sometimes you cant help them and they have to fight and suffer on there own to see the right path.