Hi Jstar... sorry to hear your H is making things so complicated for you and not being there for your kids emotionally or financially! How rotten! Glad to see you contacted a L.
Like everyone says above, dont be so hard on yourself. You have a lot on your plate and you are handling yourself pretty well considering!
My only advice would be to detach yourself from him. I wouldnt contact him regarding the kids visitation. He needs to feel like he is unwanted or not needed. Let him call you or text you and ask to see the kids. Turn this around so that he needs to ask you when a good time is, and let him rearrange his schedule. Let the L handle the financial aspect, as he should help you out with your bills. Glad to see you found help watching the kids while you are back at work.
keep your chin up! and pat yourself on the back for taking care of your kids and working! You should not want him back for the child care services or for financial support or the car.
Like you mentioned above start living the life you want! Make it happen for yourself! Start a piggy bank for your car... you now have help with the kids... start turning this around so that you will be happy. And let him figure out his own mess of a life for now.