How does he feel about going to NA or AA meetings? That would help!!
He was on opiates, right? From what I understand that is extremely difficult to kick, and almost impossible to do without lots of medical and psychological support. Has he been to a doctor? Preferably an addiction specialist?
Can he call the outpatient clinic he was at last time to get some support and guidance?
Well, all you can do is take care of you and the kids anyway. Remember, look at his actions for signs of 'progress' and disregard the words--especially if the two are not matching up.
One day at a time, OK?