Yez,
I think it is so important that two people in a relationship view and treat each other as equals.
In addition to the risks to you and the children, being so intimately in the sphere of a drug addict in early recovery, there is also the larger issue of equality between husband and wife.
He has done many things for which he is ashamed, he struggles with self-loathing and guilt, and he has lost so much of what a man needs: confidence, pride, a healthy masculine strength.
If he moves back in, under your eye and your regulations, I can't see how that would ever help him rebuild himself.
However, on his own, working a strong recovery, doing service for others which builds self-esteem, achieving success on his own two feet in his own way, he could become a man again. And meet you as an equal. A sober man who has forged a new life for himself and has worked through his dark past, on his own, and come out head held high.
I would allow him that opportunity.