HOW SHOULD I HANDLE THIS PROBLEM...HELP PLZ?

my brother troubles me soo much, he is 20 and im 18, he threatens me all the time like im gonna break your nose, bash your head in stab you while you sleep, then he hits me, the last thing i want to do is have to fight my own brother, now this is not shuving i mean i would want to bust him up soo bad, in my anger i dont know what il do.....once in my rage i picked up a knife, he foolishly thinkin i wouldnt do anything ran towards me, my mum stopped it just, i dont wanna hurt my mum by doin something terrible...plz help this has gone on for ages, should i call police, but he just says i dont have the guts to and my mum starts crying to make me not to, plz quick,