Helping an adult child who is an addict

My son was jailed for 14 months for felony grand larceny. He was a crack addict and alcoholic. He is going to be released in three months so we want to prepare for him. He says he is thankful he got jailed so he could get cleaned up and he says he is never going to go back to using again. He there are lots of drugs in jail but he has been 100% clean for 8 months. We want to help him but know how strong his addictions are and that what he says doesn’t always mean much. We want to him to go into a halfway house after his release but he wants to come. He is 28. He says those places are full of junkies and that they are worse than anywhere else. I am concerned that if he comes back to his old neighborhood that the temptations will be too much for him. He has never been able to stay clean for more than 2 months in our neighborhood since he was about 18. What would you recommend for a person in his situation?