i really need good advice, my best friends addicted to meth?

okay so my best friend, he has been doing meth for three years now, he’s 17. I thought he was just taking adoral, cause that’s how he explained it. then 2 days ago in my car he whipped out a pizo and tried smoking meth in my car while i was driving down the freeway.. i didn’t really know what the hell, so i told him to stop or i’d take him him.. then we went back to my house and he kept trying to hit it while my baby brother and sisters were home… and i was like wtf stop, and he was telling me how he wants to go to rehab, and how he’s been smoking a lot of meth for a while now, and i had no idea it was that bad. so me and our other best friend got together and we decided we were going to talk to him, and we came to the conclusion if he doesn’t stop with the meth, we cannot talk to him or have any contact with him, because we can’t put our selves in those situations. then today his cousin called his parents and told them that he smokes meth… well his parents are being completely ridiculous, they don’t believe he is smoking it or doing it at all they are completely in denail.. he needs help he’s 6’3” about 125 pounds, he looks sick. Well, i’ve been thinking about calling child services and telling them,because i talked to them and asked them what they would do in that situation, and they would go in and drug test him, and if he refused or was positive they would take him to rehab regardless but i don’t know, i told him that i can’t speak with him till hes clean then he called me stupid and other names but i do love him and i want him to get help and if his parents won’t help him then how can i get him help