Where to start?
You have to get some rest and take care of yourself. Your little ones need you. Can DH work an extra job? There are programs in the states for situations like this please don't give up looking yet. Ask, ask, and ask again.
You're going through some deeply trying times. I'm not so good at offering financial advice, but it seems to me that you cannot bear the burden all by yourself. You are strong, but it sounds like the pressure has built up to such an extent that you're about to blow. Maybe you could start by cluing in your DH? I don't know whether you need to seek professional help, or whether you can afford it. But keeping it bottled up isn't going to serve you.