Cover your bases: get him to see a doctor for depression (use a free health center if you don't have coverage), get him to see a career center for resume and interview skills and set him a deadline by which you expect him to either have a job (ANY job) or pull his weight in other ways (standing in line at the food bank, putting in applications, actually GOING to school instead of talking about it) or you will kick his butt to the curb.
I normally would be much more lenient, but if you do not have enough money to drive to work or buy food, you don't have the luxury to be choosy.
He needs to start working one way or another and if he can't find employment, he at least needs to work for your family.
As for the smoking: how you could possibly spend money on cigs when you don't have food for sack lunches is beyond me. Get a grip of reality and do what you have to to feed your family. At the price of cigs today, I can prepare a warm, balanced meal for 4 for that money.
You have to take charge of your life and you can make it better!
Good luck.