I have known a lot of addicts and not one of them have got clean without working hard at a program. Even then it can take several attempts....if ever. It sounds to me like he is just swapping one drug for another and blagging you hun. He's on a slippery slope and you're on a merry go round. You need to get off and take care of yourself and your kids babes. Your daughter at 4 will easily make new friends! I know its hard but it will be harder on you and her in the long run.
Hugs