Did anybody notice that in one of his replies that he "got him to quit cutting himself"? That is a very bad sign of severe mental health issues. This child needs help, if not thru his own parents/family then thru you with the help of your parents.
I watched my best friend from childhood turn into a drug shooting addict and I did nothing, at the age of 30 she had the heart of a 60 year old because of infection from using dirty needles. This killed me, why didn't I say something, her parents were just line my parents. I could tell them anything, but I kept my mouth shut. Why did she go on this track for her life??? Her brother was murdered by his soon to be mother in law on a beach at his family's beach house in the broad daylight by shooting him in the chest with a shotgun. Her parents were on a cruise and they couldn't get in touch with them for days. She had to carry this by herself for a long long time and she was only 20 years old. I had watched her go from Pot to Hash to Heroin to Dilaudid......when I saw the Heroin, I cut a road out of that apartment so fast and never went back, never did anything. She was living with the biggest dope dealer in town and I never said a word to anybody....why, I don't know....oh How I wish I had turned them in or at least spoken to her parents. I could have helped or tried to help, but as you all know, People Can NOT be helped until they want help. I was very immature and should have known the right thing to do. Even though her parents loved her beyond belief and gave her everything she wanted, a new car every year, etc....she never felt loved and that was her problem and then seeing her brother murdered in front of her just cut the last thread. She is still alive today and we are 50 years old, but she won't be around much longer because she did such damage to her body.
Like Jimmy Buffett's song, I smoked my share of grass and Hash a couple of times, but other than that....I wasn't stupid.....I wanted my brain to be intact. Then I married a police officer and of course I had to give it up

But I had already done that anyway but I was with a couple guys once that tried to get me to put a lid of grass in my pants because "they wouldn't search me"...HA...I told them hell no and after being pulled over by the cops and being rousted, I made them take me straight home....I wasn't going to mess up my life for just "a good time".
Get your friend some help, whether with your parents or his or if you know no one else a counselor at school or church that he will talk to. I am PROUD of you for trying to have the courage to help him, but your friend has some mental problems that you can not take care of, he needs professional help.
Good luck and keep us posted on what is going on. I will remember you and your friend in my prayers tonight and for a long time!
Mary