He needs to admit he has a problem and seek help. And avoid everyone to do with coke. Delete all there numbers and come off social media, and take up other activities.
Im in the same situation but i dont get my self in debt and you could say i have it under control… well sort of. Im lapsing once a month. And im 4 week clean today.. but he needs to change his lifestlye top to bottom.. and cut out every one to do with drugs. But the main thing is he needs to want it.. and more or less hit rock bottom.