Jail can change people for the better or in, some cases, make them worse. He can continue to use drugs in jail if he really wants to. They are much more expensive than on the street but it happens. Hopefully, his jail will have some sort of rehab available to him in there. He will have a lot of time to think & so will you. My addict cousin has been in and out of prison close to 20 years & he seems more comfortable inside there then he does in the real world.