This situation is spookily close to how mine was: combination of psychopathic older brother and weak parents.

My brother is a psychopath. He delights in causing upset and distress in others. Making others suffer is immensely pleasurable to him. During my childhood, the physical violence from him started when I was 12 with punches and the like and ended with him trying to strangle me when I was 18. I couldn't do anything but feel that I was losing consciousness and he most certainly would have killed me if my father hadn't been there to get him off me. The only thing my brother could do the next day was to mock the squeaking sound of the air that my lungs could force past the strangle hold to alert my father. Needless to say, I got out of that house that day, and lived in my car for a week until I could find somewhere to stay.

During my teenage years the emotional abuse I suffered at his hands was unbelievable. It was a living hell. When I was around 16 I realised that my best chance lay in not rising to him, so I ignored him completely - I said nothing to him and did not even look at him. Still the abuse continued, but it was slightly less.

During those years, my parents would throw him out of the house for more minor abuses that he did to them, but as they were weak they would always let him back in the house. And he would always act out again. He would vandalise their cars, destroy their property, steal from them etc. The final straw came for them when he pulled a knife on our mother. Then he was kicked out for good.

So, when you have an abusive, psychopathic sibling, my opinion is:

1) They are like a cancer. It must be cut out from the body (family), otherwise it will destroy part(s) of that body or the body itself. There is no trying to treat it or seeing if it will get better. It won't - they must be extirpated and discarded

2) You need to get out of that situation NOW. Wherever you go, it will be better than living in that situation. When you reach your new destination or residence, you will breathe a sigh of relief and ask yourself why you didn't move out much sooner

3) You have to cut all communication with him. Don't acknowledge his presence, don't talk to him, don't even look at him. You recognising him as a person and as an abuser will only fuel the fire

4) Be prepared to cut him out of your life, for good

5) When you've done all that, pick up the pieces and let the healing process begin. Nobody deserves to be victimised like that