Liesagain, Honey I am so so sorry. I might start by seeing if you can talk to one of the counslers that he was just in treatment with. They might be able to give some input to see if he was just BS ing while he was there or if he was really working the program. I don't know if it would matter to you eaither way.
How old is the child & how long have you been a part of his/her life? Noone can tell you what to do, I might suggest not making any quick decisions. You need to do what is best for you, but also go slowly with the child since he/she has already been moved around. Addiction just sucks.