I know how hard this in and out business can be. It sounds like everything came unglued for a bit due to his decision to be a part of your life again. I agree that you need to take back the reigns and put the focus back on you.
I would have a hard time with his 'attitude' about being out late. IMHO he should be kissing the ground you're walking on after everything he's done and how much he's humiliated you.
I too know how easy it is to be roped back in with all of the 'right words and right behavior.' It sounds like an act to me because he wouldn't have pulled the out till midnight with an attitude stunt. Also, the crack***** should be 100% out of BOTH of your lives and he should be doing everything to ensure that this happens, especially because her entrance to your lives is @ his hands.
Take the power back. Take the focus back. Put the walls back up and work on you and your kids. It's tough, I'm sorry you're going through this.