You made what you considered to be a wise move for the welfare of yourself and your kids. If he really wants to change, he can do that without living in your driveway and regardless of whether you "wait" for him. Tell him it's wonderful that he is planning to change and that you are sure your kids will benefit greatly from his sobriety. Tell him you really look forward to their having a sober dad someday.
And if it were me, that's all I would say. No to living in the driveway, no promises about what you will or won't do. He's trying to negotiate/manipulate what you do, rather than just going out and DOING what HE needs to do.
Quack is right.