First thing, keep that check book away from him! Close the account and open a new one. Don't even bother ordering checks, there's nothing you have to pay that you can't pay online or with a cashiers check or money order. Don't let him get away with taking your money and putting it in his accounts. I have a huge problem with joint checking accounts for this very reason, one or the other will try to control the money, therein controlling their spouse.
and no honey, your kids would not be better off without you, a child needs it's mother and when you feel as though you can't go on, look at those faces to remind yourself of how much you are loved and needed in this world. My kids are my motivation, my reason for breathing and the love of a child is a powerful thing.
You are of worth, you are needed and wanted.
Don't give up. Stay moto and be the best mom you can be