guiltiness

Sigh.... recently, i found out that someone whom i really cared a lot for has been smoking and drinking hard. REAL big time. I was so surprised that he's slowly turning into an alcoholic and a heavy smoker. So i've heard, Vodka, Cocktails, has been his "sky juice" on a regular basis. Growing into adulthood, i guess there's this transition state where one will find his or her own identities, having frequent arguments with their elder ones (parents), relationships, friends and studies. I wonder which category/S does he falls in?
I'm feeling rather bad and guilty myself for shutting him away each time he needs me. Sad to say, his messages that he sent to me telling me about his problems will be cut short by me with the ," sorry dear, i'm busy. I'll get back to you?" But i never did. Not returning his calls. Not even a SINGLE message. T.T Somehow, i felt that i might be a part of his reasons for his unhealthy habits. Not being able to reach out to someone whom can lend their ears too, that might be a reason. So, he seeks alcohols and cigarettes. 5 days of alcohols and God knows how many packs per week.
I also found out that he can actually inhale in 1 breathe, and exhale out the smoke, leaving behind only half of the cigarette bud in 1 shot! Seriously, i have no idea how to talk him out.I wonder if i can...