Food stamps can give you benefits within 24hrs if you no money coming in. Also you can sign up for WIC and they too can give you a card immediately to buy dairy products and fruits/veggies.
In most places you can get food stamps same day if you have no expected income amd sometimes even if you do. If you can't go your fiance probably can. There's also the food bank amd other resources depending on where you live.
I'm sorry that sounds really stressful :( I hope you guys figure something out.