(((Hugs))) and welcome.
Just a word of caution, letting your stbx use your home may make the situation more confusing for your kids. You are allowed to say no. He should be living within his means, including choosing a menu that he has the facilities to make.
This shit is hard and I sucked at breaking away and maintaining NC in the early days. It wasn't until I went full NC that I was able to start healing. I understand that you have kids and are trying to make it as easy as possible for them. Unfortunately i worry that they won't start to fully accept the change until they see a clear break and are given time to adjust.
It is good that you are removing yourself from the situation. Me: Awesome - 35.... ummm, not anymore
"I’ve learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel". –Maya Angelou