You could look at moving to a cheaper area out in the countryside, where rent/mortgage is much lower. If any of your skills are suitable for WFH, then you can still charge city rates for them. My DS-i-L did this. Moved from London to a tiny coastal village and worked PT from home for her old law firm while DC were growing up. It was a very stress-free existence.
Start by working out what your most valuable assets are. Is it skills that command good hourly rates that you could use form home? Is it a city property that you own?
I would be very careful about moving to the middle of nowhere. With nothing to entertain them, DC could get very lonely and bored or depressed and you could feel very isolated. You could end up driving them around everywhere and really scrabbling to earn a living on seasonal minimum wages.
Make a note too of all the good things in your life that you take for granted. Are there good nurseries. schools, healthcare. transport, local events, well-stocked, fairly priced shops and markets, supportive friends or colleagues? If not, then the move will be easier. But if there are, don;t underestimate the shock of isolating yourself from all that.
Meanwhile, ease off a bit. Have a day in the countryside this wekend with the DC, just to see how they enjoy the mud and frost and wildlife. It's all very well fantasisisng about home schooling and allowing children to run free but not all children want that. Some long for structure and clean clothes and central heating. Would an alternative life style suit your children's personalities?
Maybe chat with your work about doing a day or two from home each week, or going down to a four day week so you are less stressed (the savings in childcare and commuting bills can make the loss of income more bearable.)