Helpless
I am so sorry to hear this and my heart hurts for you because I know how much you worry about him.
Obviously don't take anything he says personally because when they are using drugs their brain is not right and being sober for 2 weeks does nothing to help them really.
My son also wanted to leave at 2 weeks but they talked him into staying and he knew we would not help him/be in his life if he did NOT complete the program and that we meant business - so he stayed and said he was glad he did. My son was a horrible person at that time and I loved him because he was my son but I literally hated him too. I'm not afraid to say that.
I will pray for you and your son but honestly I would not help him at all if he isn't working towards sobriety. I know that is very hard because we had to do it also but if we had not done it he would still be stuck where he was. I understand you can only do what your heart will bear.