Drug addict

He asked me not to tell his sisters they could be heartbroken as he was the only son in the family and he said they might believe me or not but they would think im jealous of him for his archievements in life. Ok he works, he had a car he sold it to fulfill his cravings for drugs, his sisters doesnt know the reason behind him selling the car he complained that it was draining his pockets whilst the real reason he sold the car was to get drugs.... He is light in complexion but he is turning dark.... He said to me if he doesnt get the drug as soon as possible it would be difficult for him to sleep... 

So i need advise, should i tell her sisters or not and save the relationship we have between me and my cousin  because its clear he is going to hate me for doing all this to him or should i let him be? The only thing thats pushing me to want to tell about his addiction is that he just recently got a job as a train driver at a well known and well paying train company he got the job by struggle... In SA lots and lots of youths are unemployed because we lack resources to create jobs.... He is a breadwinner at home everyone in his family is depending on him..... If you were in my shoes right now would you tell to save his job and get help he needs or would you let him ruin his future because its clear he doesnt care much of the opportunity given to him to have a well paying job?