Breaking up with the father of my baby?

well me and my partner have ben having problems SO much over the past 10 months we have been together 21 months and we have a 7 month old baby. he was SO sweet at the start he is a weed smoker which i hate and am totally 100% against i don't Smoke or drink im a family person he is the complete opposite of me he loves our baby and he loves me but he wont give up the smoking he keeps saying he will but he wont end i don't get any money from him he offers sometimes then complains when he is broke that he cant by more weed. he said he would give up weed/smoking when our baby was born till then i Had to deal with it even though im an asthmatic well when our son was born it didn't happen . ive been really depressed lately i cry coz he makes me feel like **** he blames our problems on me everything is allways my fault he has had me cowering in corners when i was pregs....i love him but i dont think thats enuf to stay anymore he is lazy he looks on the net for a job and then says he is tryin but its not. every one thinks he is Innocent no one sees what he does to me and that makes me really upset i feel stuck like ill never get out i know one day soon he will hit iv been through it bfor in the past he has allready gone to once bfor .. his brother has just goten out of jail he rings me up talking to me like **** and then goes and tells my partner it was me but its not im allways very polite to him despite the fact that he just finished a 4 year jail sentence .. im a lil scared that he might hurt me if i end it with my partner i have just moved out to a save location SO no one knows were i am but stil im scared. i feel like theres no hope for me in this relationship i don'tknow what to do i have ended it once but he cryed and made me feel bad so i stayed. im stuck .im really hoping somone might be able to give me some ideas please