Hi Twinklebug,
First of all, I'm so very sorry this has happened to you. I will also caution you by telling you I am very blunt in my advice...my BGF (best girl friends) call me "the checker" because I'll check them every time they do something dumb and I'm lucky...they also check me.
The least of your problems is the car insurance. Yes, it may feel that it is the most pressing since it is "due" today...but you have much bigger fish to fry! You really need to get your head out of the sand and be the grown up and call him to make sure he isn't dead or missing. If he launches into a diatribe about what a horrible person you are, don't react...just simply hang up. You obviously already know that he is a rat, but at least you'll know he's not a dead or abducted rat (i.e., a rat that needs a missing persons case opened). By the way, if it's any help, I'm sure that 95% of what he says is how he feels about himself...not you!
You also need to open an account that is yours and yours alone to deposit your checks into so that he has NO access to them. Get to your HR office NOW (if your checks are direct deposited at the end of the month like mine are) and ask for a paper check this month or ask for it to be deposited to your new account (which they may or may not be able to do). If you have a safe deposit box with valuables in it...open it up and make sure they are still there. If they are...MOVE THEM! Don't let the rat keep on taking from you.
Call your joint credit card companies. Verify all the balances. If you are the primary card holder on any account, have his name removed (you can do that). If you aren't the primary card holder, then verify all balances and keep a journal of what charges are "yours" from this point forward.
Change the locks on the house. You can take your locks up to the hardware store (like a local tru-value or ace hardware) and they can re-key them, which is a lot cheaper than a new lockset!
Finally, I know you say you are "scared" to talk with a lawyer. I'd say that's silly. You need to talk to one and talk to one NOW. Lawyers are NOT scary people...they don't have 7 heads....they don't look like monsters and they won't eat your children. What a good lawyer will do is PROTECT you. Most family/divorce lawyers understand when a husband leaves and cleans out the accounts there is NO money with which to pay and they'll set up an affordable payment plan for you.
Now, I'm not saying that you're ready to divorce the rat -- it's definitely a process to arrive at that decision. But you DO need to know how to protect yourself, your assets and your kids and also make sure that the rat continues to support the children you share.
Good luck and let me know if I can do anything to help....I'm cheering for you!!!
Karen