He is an adult, he needs to manage his own money, buy his own gas, food, lodging. It is his responsibility to take care of himself.
Is he contributing to the household? Is is he supporting his children? Has he earned the right to come back home? Or, are you making it easy for him to be irresponsible? If you say No to any of the first three questions then I would say, you are enabling him.
I don't have the answers, only you do....to me, the first priorty is to your children, their life, not his.
Just my two cents.