but I don’t think anyone has any more factual information on their split than anyone else
You seem to think YOU have more factual information on this case than anyone. Which is why posters keep asking if you're Helen!
Going on past legal precedent, however, it is unlikely a healthy adult woman of working age with three school-aged children would be allowed to stay in a money pit of a house which far exceeds her needs if her ex partner (who she never married) cannot afford it.
Even if he can afford it, courts do not generally side with one partner who wishes to use their ex as a cash cow forever more.
Far better for her that she gets out there, gets back to some form of regular work and starts to live within her means - which may include a nice, unmortgaged four bedroom house.
If you feel that is in some way horribly unfair, you can always start a Crowdfunder for her. Am sure it will make a killing.