Hi Arrow. Sounds like a bad situation. Sometimes I wonder if it's worth replying because OP's hardly come back to this site after posting their problems...
Anyway - back to your situation. It sounds bad. MIL threatening with knives and a baseball bat?? Husband out of work for almost a year? Is he actually going to find work? Is he looking?
What are you doing for work? Have you got some kind of income? I'd be taking Pipsy's advice and checking out options through Centrelink and finding out your position and entitlements. Do it all without telling anyone.
Try to keep out of the house as much as you can and most importantly - have an emergency bag ready to go. Have all your important documents safe and secure. Just in case something bad happens, you need to be able to exit quickly. You cannot live like this.