She is getting a benefit whilst he is incurring the cost and being deprived of that benefit.
Not really. This 'benefit' is costing her money in terms of the mortgage plus maintaining the property.
She has 2 DC. Who are with her 13/14 nights. Of course they need somewhere to live.
No, she has no right to assume she can decide what happens with the property. That's what mediation & legal proceedings are for.
I can’t get over this idea that she can make a unilateral decision to benefit from living in his share of the property without paying for it.
How is she doing this? 🤔
She's housing herself & DC right now.
Her ex can decide he wants to sell the property & divide equity, or request she buys him out. These are all reasonable courses of action.
What's not reasonable is for him to prioritise his own living arrangements over those of his DC
of course, if she refused to engage in discussions and just expects him to pay indefinitely, that's also unreasonable and it did appear that she was suggesting this in her OP.
In other words, they both need to come to an arrangement. He can't just ignore that he has a financial commitment linked to this property in the meantime.