Stop worrying about what if this and what if that. You both will figure out the child care and if the kids go to a babysitter then they do. You can't control everything she does and you don't want to either. You state your needs in regards to the child care and so will she and you compromise on certain things. Either that or you can go through courts and have a set schedule to avoid having her walk over you. You do have a say in the way things are handled too.
Also, as far as the whole "I can see it's going to be a struggle" no ghost, now is the struggle. Is like your worried about moving closer to the equator because it will be hot but you ignore thr fact your living in hell right now. It will be better in so many ways, just trust you are strong enough, or will become strong enough, to handle it. You're still scared and thats understandable. This is going to be new for you just as it was for me. I spent a long time fearing being on my own but I recognized it would be good also. It's going to be lonely in some ways but trust me ghost, your going to find yourself and when you do your going to feel amazing. I have the grief and pain of what I did wrong in my M and I wish I could go back and change things but that's not how life works. We're all human and we all have made mistakes and we will all make more mistakes. You learn from these mistakes and move forward with your life.
Accept what is, let go of what was, and have faith in what will be