Under constant harment and i cant take it any more need help!?

about 2 years ago i had a friend in college we were close but a year ago we had a falling out he was taking drugs and i didnt like it so i moved on .he called me a few time and i told him i want nothing 2 do with him and i changed my number and deleted him from fb so he couldnt contact me any more on November he found me through some of our mutual friends. he was with 3 of his friends and wanted to fight i tried to stop him but they beat me up in the street i was beat up pretty badly and ididnt know why he was so mad . i didnt really get any hit on him or any of his friends but i was hurt pretty badly . i didnt report it or anything i just tryed to forget about it .he tryed to get in contact with me through the mutual friend but i didnt reply . i though it was over and done with and i would never see him again . a month ago i see him out side of my college and he aproches me he askes me plz to talk 2 him aand he apologise says he was on drugs and didnt know what he was doing i said its ok we talked and told him to have a good life and walked away thinking i would never see him again but again he shows up at my college and ask to talk 2 me i dont want to start anything and out of fear i say yes and hope he will just leave me alone after . i dont tak much and then make a excuse and leave . now again he tries to contact me and through the mutual friend he says he need to talk to me and its important . im afraid to call him and i know hes gonna come beat me up again .... idk what to do . im scared now i have friends and a brother who can help me but i dont want this to go any further i just want it to stop i havent told any one whats happening from fear of it getting any bigger . but what can i do if it was only the pain of beating me up i could hanndel but its also the fear he can find me its not hard and i have exams now that i need to focus on what do i do ???. who can help ??? the police but idk if they will really do anything and idk when its coming and that wont solve the fear part