Oh, Huggie, I am so sorry.
Going from a two income family to a one income family is very tough...
But you can do it.

Your girls will benefit from having you there so much and kudos to you for not giving up the afternoons you spend with them.
I was 8 months pregnant with Drew when we decided I wouldn't work anymore. We went from having lots to having very little for quite some time. There were times that we had no money for groceries and put everything on the cc. But we survived, and you will too.
Shelly is right. Cut back on as much as you can. Go to the grocery store once a week, not 4 or 5 times. Plan your meals for one week out, or if you can do it, two weeks out. Make a lot of one thing, say chili, or spaghetti or soup. Then eat it again later in the week. I still do this. Monday, Tuesday and Wednesday, I cook. Thursday is always leftover night in our house.
Eat out only once a week. That includes ordering pizza out. If you cook at home, you usually can get 2 meals out of it instead of one. Pay cash for your groceries. However much you budget, that's it. When the money for that is gone, it's gone.
Rent movies, don't go out to the movies. Get movies from the library (they're free!).
Use half of the laundry detergent that's called for. For a large load, only use 1/2 of the measuring cup. Run the dryer at night. Don't let the dishwasher run on the "dry" cycle. Wash clothes in cold water.
Put your thermostat up (or down!) a couple of degrees. Don't leave the tv, computer, or lights running in the house.
Go to basic cable services. Drop to the lowest minutes on your cell phone. Drop any unnecessary items on your home phone bill.
Only go out to run errands once a week, and do it on the way to the grocery store. Saves gas.
Pack lunches for your DH. No coffee runs. No donut runs. Commit to not buying any clothes for yourself for three months. When you think you can't stand your hair for another day, and want to spend $200 (that's what I spend) on a cut/color, pull it up into a ponytail! It can last another month.
No manicures, or pedicures. Give yourself one, save $50.
Tell the kids to choose what they want for Christmas. You write it down, and tell them that Santa will pick three things from their lists. That's it. After all, Jesus only got three gifts from the wise guys!
Instead of buying precooked items (frozen waffles, etc.) get some bisquick and make them yourself. They freeze wonderfully. Buy a ham. You can get a LOT of meals from that one purchase.
Wash your own cars. Mow your own grass. Clean your own house. Pay bills online instead of sending them through the mail.
Okay, enough for now. I'm getting obnoxious.
You can do this, Huggie. prayers to you.
Jo