Sorry to hearthat you're going through this bamzooki.
From my days as a family lawyer (a wee while ago now - but can still remeber a bit) you should:
Make a list of all your assets and debts - in your name, your husband's name and in joint names
Include everything: house, cars, bank accounts, savings, investments, shares, credit cards, loans, store cards - just anything you can think of. Have as much detail about each one - account numbers/addresses/whose name it is in/ when account or debt opened etc. Have details of your H's pension and your own.
Take in your marriage certificate and the children's birth certificates
Have details of who is paying for what now that your H has moved out. Think about how much you would need from your H in the future - can you afford the mortgage/rent or will you need continuing support from him
Make a list of your monthly outgoings and a note of your income.
If you can, get details of your husband's income and details of whare he works.
Ask about changing your will - if you already have one, bring it in with you.
Think whether there was anything financial pre-marriage that might merit a mention.
Good luck