I am so sorry to hear the stress you are facing right now. Kudos for you for trying to hold the family together and for caring about your husband and family.
I don't know where you can get money, but I have some ideas for earning/saving some because my husband and I have also been in a tight spot before. Do you know anyone who would pay to have their house cleaned? Family who was not struggling financially would always hire me when they found out I was willing to do pretty much anything to earn a buck. When they could see that I was willing to work hard they would give me extra stuff to do like wash their car, babysit, etc. The little bits of money can add up quickly, especially if all you need is $300. My mom wasn't rich, but had more than we did at the time, so we worked out an arrangement where she would pay for the food if I did the work grocery shopping and cooking for both households, and then my husband and I would eat for free that way and didn't have to buy as many of our own groceries. Growing up my mom always babysat other children to make money while still staying home with us children.
Beans are super cheap, super healthy, and super easy to make. I make a large pot and freeze half for future use, then eat the rest of it all week. First I'll blend some to make refried beans and we'll have tostadas. Then we'll have burritos the next night, then taco salad another night, and with the rest of the pot I add some canned tomatoes, corn and veggies, and spices (and a tiny bit of meat if you can afford it) to make some chili and cornbread out of the rest. Bountiful Baskets, a food co-op, is a great resource for buying inexpensive produce. It's volunteer run and they cut out the middle man (grocery store) and for $15 you get a large, overflowing basket (I bring my laundry basket to bring the food home in) of half veggies/half fruit that lasts my family two weeks. I love the variety (you don't choose what you get) and freshness. My sister and I split it sometimes because it's so much food. www.bountifulbaskets.org You can google recipes online and make your own laundry soap. It's much cheaper. I make the dry version since it's easier than the liquid version. It doesn't work as well as commercial laundry soap since there aren't as many chemicals and stuff, but it works. I throw vinegar in the washing machine for fabric softener and I promise it does not make clothes smell like vinegar one bit. Many people use vinegar if they have allergies. It can also be used as a cheap, nontoxic cleaner.
And one other money-saving tip which might make the biggest difference -- if you're struggling paying your rent, maybe find a cheaper place to live. We lived in a crappy tiny apartment in a crappy neighborhood for a couple years, but it was what we could afford and was less stressful than living in a nicer place that we couldn't afford.
Good luck! I know you can get creative and make it happen. I'm rooting for you guys! Please give us an update in the future with how it turns out :)