I think they mean $1000/week, which makes more sense considering the character has two children. But who would get approved for a $4.3k/month mortgage on a single earner getting paid less than minimum wage?
As I noted in another comment, it's "due this week" not "due every week". Given the portrayal is definitely someone just scraping by, it's possible their cushion for the mortgage was just eaten up by some other non-negotiable expense.