Do you have anything you can sell? Can you take an evening job for six months to build up a cash float? Is there anything you can cut back – gym, phone contracts, takeaways, hobbies etc?
Can you all stay living where you are and agree evenings where you stay out or she stays out? Swap rooms around so you share with your son or she shares with your daughter.
Our local council has a furniture refurb scheme where things are available for a £ or two. Try that. Charity shops for curtains, pots, pans. etc.
It isn’t easy but you need to work together because it is in both your interests to resolve it.