I agree. My daughter and her husband live in a rental house that his parents own. She's in her last year of pharmacy school, and when they got married, his parents offered them their choice of the two rental houses that they own. DD and DSiL put $4000 of their own money into renovating the house.
I can promise you that there is NO way they would deal with anything like this. If they were told that they had to let someone live with them, they would move out. It would be very difficult since they have to live on one salary, but they wouldn't deal with any of this madness.
I doubt very seriously that your mother will put up with them long. Where they'll go then -

, but I wouldn't be surprised to see them back with you unless you make some choices on your own.