If a judge were to make a ruling like that, it could be taken that it's ALWAYS the dad's obligation to help the kids to have a place to live. That makes for a very unsettling precedence. Stand your ground...yes, part of the CS is for housing, along with food and clothing, the necessities.
Did she sign anything saying she would pay it back? Because if she did, that makes it a binding contract. And if she can afford an atty. to get her out of this one, what did she need the money for in the first place?