Who is Bill's wife and children from Junky and what is their importance?

Bill is married to an unnamed woman by common-law and has an undisclosed number of children. His wife is mentioned only a few times in the text and the children referred to only indirectly. Bill and his wife were apparently married before the beginning of the novel. Bill's wife is incredibly long-suffering and tolerant. Although she does not use drugs, she remains with Bill for several years through his addiction, appearing from time to time to bail him out. Her main objection to his drug use appears to be the inactivity it causes. By the end of the novel, even her patience has been expended and she has left Bill and taken the children. Bill mentions this as casually as he mentions meeting a new junky.