Originally Posted by
i4getsm 
He's keeping the kids tomorrow night at his parents' house. Says to me bring them over anytime...the sooner the better.
Hope this doesn't sound too harsh, but the first things that came to mind was, he's manipulating you to "look better" as he knows you expect him to be his old lazy self and the second thing is, his parents will be there, thus giving him more freedom from the kids.
Alcoholics are good manipulators and know just how to hook us. Maybe he knows what really bothers you and thats the fact that he lacks taking more interest in the kids.