Hun he is not your responsibility. He should be paying 30% rent and bills (since there are 3 of you living there) and pulling his weight with his share of the housework. What is he doing with all his money? Single rate of disability is about $600 a fortnight which is pretty crap... unless you are living entirely bill free
There is a saying by Einstein I live by. "The definition of insanity is doing the same things over and over and expecting a different outcome. " Nothing is going to change until you put your foot down. Tell him he either starts contributing or get out.