A depressed person getting dependent on me!!?

there was this guy in my work place who sometimes used to talk to me over the coffee machine and in front of lift..he was decent so even i used to talk to him casually. He slowely started taking about his depression with life..my problem is that I dnt take him as a friend, but he is getting dependent on me. He has started saying things like "miss you".I am afraid if i say somehting to him, i might pust him to the brink..He said he has even taken professional help, but the antidepressents caused him hallucinations..what to do,,i dnt even want to be rude, but i cant be close to him..