Sell one of the cars; the used car market is pretty good. This would give you some immediate cash and your car insurance would go down. You can get another car when it gets better. You may have to double up on some trips, but it still would be cheaper with one car.
As far as your business goes try something new there. If what you are doing isn't working then try a new concept and open a different kind of store in the same location. You can always ask the landlord how he can help you, too. Maybe, he would let you out of your lease; you never know. Maybe, you can sublease it. Check out options. While your husband is looking for work get him to help at the store with whatever you decide to do there. As others have suggested if your skills are more marketable then maybe he needs to take over the house and business; so, you can get a full time job with benefits. Don't know where you live, but maybe he can shovel snow or do lawn cutting, etc. to bring in extra money. Take a part time job; my son in law has been doing this for a couple of years, now. He's a laid off engineer. He works part time for Federal Express.
Be frugal. Learn to use one room with everyone to cut down on lights and such. Use blankets instead of turning up the heat; learn to wear sweaters and such to keep warm around the house and turn that thermostat down. Share the TV and everyone gets a turn to watch their favorite program, but don't use multiple TVs. Learn to use the library for free entertainment. Ride bikes and use the community pool for fun activities. Go on picnics. Use cheap soap for cleaning. Dilute everything you can like buy 4% milk and use water to make it stretch. You can do this with all kinds of drinks; except, soda would not be any good this way. You don't need to wash clothes as often. We've learned to wear the same outfit more than once. Unless, you are doing something that gets you real filthy or stinky you can rewear your clothes. This holds true of towels, too; reuse them. Don't go out for meals. Learn to carry a lunch to your retail store. Eat cheap. This means stretching everything with rice or pasta. Do alot of soups and make them into stews by adding whatever to them. Beans are a good source of protein. Peanut butter sandwiches will have to become a staple. Eggs are cheap as a source of protein; we have omelettes for dinner. Bologna sandwiches will get you by for the meat taste and hot dogs will suffice. Buy everything on sale and stock up on items that you will use over and over again like toilet paper when it's a good price. Get away from name brands on everything. Go to garage sales to buy anything you need. Goodwill is another good place. Take hand me downs from relatives and such. Get away from buying anything prepared even a cup of coffee; make your own.
Maybe, your daughter can help more at home. I would think she could make peanut butter sandwiches for everyone. These little helps would give you more time to do other more important things. She may be slower doing it all, but everything will help. It will help her become an adult and be more self sufficient. If she can't do anything then I would get a lawyer to fight your disability issue with her. Maybe, you need a stronger statement from your doctor about it.
Relocating may be the only answer to find new work. Maybe, there's family in other parts of the country for hubby to look for work. Maybe, a family member can give you a positive lead. You may have to take less pay and you may have to do something new to get by. I would ask family for help; what do you have to lose?
There are no easy answers; I'm sorry.