See my other post on the children.
The only thing you can do to make him help you with bills is to sue him. It can take up to a year to get into court. Is his name on the mortgage of your house? Is his name on the deed? Regardless of the above 2, if he lived with you more than several years, he may have a “marital interest” in the house.
You can be held responsible for the things he bought until you “officially” separated.