(((hugs))). Welcome. I'm so glad you are here.
And I'm sorry that you are in such a spot. Don't worry about the bills. In the big picture, what really matters is you and your children. For me, what I find helpful is to make a list of priorities and then focus on the items on the list one at a time. Safety. Food. Shelter. Electricity. Phone. etc. etc. Credit card companies should be way down at the bottom of the list. I also find it helpful to write out my goals (because I tend to forget them so quickly) and write out my Personal boundaries so I am clear with myself about what I am doing and why I am doing it. Personal boundaries are for you. They list the kinds of behavior you will allow around you and your children and what you will do if someone violates your boundaries.
Crack cocaine is so nasty. My ex is a crack addict and I was hooked on it for many years. You are in no way responsible for his bad choices to start using again. He has all the tools he needs to stay clean and sober but he is not willing for whatever reason, to use them. He CHOSE to pick up again (and once you start using crack it takes a train wreck to get you to stop - every relapse makes it worse too). But that was his choice, not a fluke. He knew full well what he was doing. And you cannot make him change.
One day at a time... and you will get through this. And by doing so, you be an example to your children of strength and perserverence. You will also teach your children that when it comes to your family, drugs will not be tolerated.