I truly believe from what you posted, that the irresponsiblity you question is a direct result, or bi-product of his major depression episode! It is obvious that he needs his therapist. It also wouldn't be a bad idea for you to go to couples counseling for a bit. He really needs to learn how to take responsiblility for his actions and not blame everything on his depression...although that is easier said than done.

I hope everything works out.