It sounds like the mom can’t afford the debt and the debt only exists because her ex-H insisted that their child attend there.
I don’t blame the mom for not “arranging for payments” or whatever. I’d give the school the exH’s contact info and let them pursue the debt…perhaps put a lien on his $3M home!!!
If I were the mom, I would figure out work-arounds…get GED, start at a CC, or find out how to create a homeschool transcript.
I hope this serves as a wake up call for anyone else that could end up in this situation.