Help to understand a friend. keep him or leave him?

ok, so iva had this friend for about a year. we dated for 2 months a year ago. we started out as great friends and everything but we slowly fell apart. I promised him a long time ago id never leave him. I beleive he's got depression but he refuses to...

accept this as a possibility. he's got an obsession with this 1 girl in his life. I'll just call her B(she's not a b*tch. she's acvtually really nice her name starts w B). so his obsession w B has led 2 him not caring about anyone else. he duznt care who he hurts any longer as long as he gets B in the future. I've been there thru so much and have always looked out 4 him and been there but he ignores me like all the others. im getting sick and tired of being dismissed when I've done so much for him and B's done so little for him. I'm almost ready 2 just kick him out of my life. but it's hard 4 me 2 break a promise. I discussed it w a mutual friend and she sed I could break that because the boy I made that promise to is no longer here. im not sure what 2 do but I don't know how much more of this I can handle. I dont think my love for him (like I love my bro, nothing more) can hold this up anymore. so what should I do?

slap him up and nock some cense into him. Im not saying to resort to physical violence but you need to put your foot down and give him a good peice of your mind show him how he is treating he's loved ones and let him know that if he keeps that up he will end up regretting it, don't make it out as a threat more of a warning, like I am worried, and tell him you are tired of it, and you never agreed to taking is abuse(emotional)
if that doesn't work let me know and I will helpyou with the nice kind slow way of getting him to turn around, but normally the fast and honest way works the best