Key priority is a roof over the family, food, and valueable family time. Without knowing more can only postulate. 5400 gross per month is plenty in some places and barely getting by in others. 90 hours a week means no days off and looking like something like a minimum of 14 hour weekdays, 10 on weekends, but could be as rough as back to back 16s or worse and a few hours on weekends.
I'd look for the cheapest feasible living conditions. Are three bedrooms needed? Or can it work with 2? Be open to mobile home living if possible
Having 3 jobs is extreme strain. Is it possible to reduce to 2, forgoing some income and still survive? Goal here is to free some time that can be redirected to quality time, destressing, and any outside hobbies or training that makes life worth living
Cut all nonessentials to reduce expenses that may be driving part of the job demands. Any excess save for buffer, family vacations, amenities, general improvement, towards a down payment on better living conditions
Reduce/eliminate items where tco is not worth it. E.g. any extra vehicles, trailers etc where insurance, registration, or other recurring tax has to be paid
Ask for what you want and need without begging or scamming. Many people want to help others and will part with items or their personal tome easier than money when they know it will be appreciated