My initial response to this is deep sympathy. I do pretty well keeping track of the money I have, but I know it would be easy to get in over my head if I had more expenses, and she's never been a frugal kind of person, so far as I can tell. I can only imagine how stressed out I would be if I didn't have the money to cover rent! And she doesn't check her bank balance and balance her checkbook each month, so she didn't even know she was bouncing the checks until the realtor called. Of course, the landlord tried and tried to cash them, so she's racked up ridiculous amounts of overdraft fees, too. Ouch.
She even offered to move out and find us a new roommate, which struck me as ridiculous, if she's getting things under control, and I hope she doesn't.
Then I remembered that the lease was signed as a "jointly and severally" sort of thing, which means that if he WANTS to, the landlord could come after me and the other roommate to cover the lost rent from the third. I really hope it doesn't come to that, because, although I know she'd pay the money back eventually, it would just be a really difficult situation all around.
This may also complicate things should I decide to try to finagle a way to get back into this apartment after my Guatemala trip, but that's hardly worth worrying about right now since I'm not sure I even want to do that, and I've got enough to think about the trip without worrying about something that I'm not even sure I want.