Very messed up situation..... READ PLZ need help?

ok so these past few months i have not been getting along with my parents (im 16 male) and my grades have been failing as a result of constant arguing , fighting etc and i have a long standing feud with my older bro(his 22) and basically a faliure with no life he has no formal education whatsoeva, He used to beat me when i was 10-13 yrs very badly and i couldnt fight back it caused a huge mental scar on me. Then he left our house for 2 years and we didnt see each other. Well basically he came back a months ago and we still dont talk much. Well today my other bro (his 17) and my mom had a argument and my mother told my older brother to beat him for her so he punched him badly in the right eye. so bro(17) came to me for help as they both were agnist him. So me and him decided to beat the living **** out of him, his big built (22 yro). So me nd my bro took him on beat him badly and carried him out the house as he was unconcious, mum called the police and the cops charged us with ult causing grevious bodily harm(just a lump or two) after a while i just felt after those years of him beating me badly i got my revenge and i felt calmed and happy.'BUT since i know his not going to let this go and beat me to death one day when im alone , super badly(he has some mental issues) .......what should i do can i move out when i have nowhere to go? Any advice? Plz dont tell me to say sorry to him i havent spoke to him IN 4 YEARS im scared he has some plan to **** me up (his not scared of the police) ?