Sad Girl is right.... whatever you do has to be done for you. You can't do things based on how you think he will react, or to try to manipulate him.
As far as being sweet and affectionate, those my have been his complaints, but I think things run deeper than that now. Clearly, that's where you do want to end up, but it might not be the most important thing right now.
I think your first priority has to be taking care of yourself. Which will in turn help you take care of the kids. I know that falls into the category of easy to say, hard to do, but it's really important.
You are right that right now he is going to see any changes in you as fake. That's why they have to be real, long term, permanent changes. And the only way to make that kind of change is to make it for you. Since you say it's really "just" going back to what you were before, you know you can get there.
I don't think you need to worry about being mysterious right now. I think you should try to limit contact. Right now, your contact is too likely to get used against you. He's looking for things to justify his decision, and as you just found out, he will find them. Less contact, right now, means less walking on eggshells, and less stress for you. Which might lead to better rest, and more sweetness when you do have contact. Though I wouldn't be trying to show sweetness so much as mature respect. Validate his feelings, avoid relationship talks. Show that you are listening, show that you are responsible. Be confident in yourself.
Once you get to that point, he may start to reconsider things. But it will take time.
