Hi Lisa: Sorry about your divorce. The stuff you're going to need kind of depends on what State you're in since each one varies with regard to divorce law. Here's a couple of things you should start thinking about though:
1) Equalization of Assets: You're going to have to prepare a financial statement. So you need tax returns, paystubs, pension/IRA/401K statements, monthly expense lists. See if you can get a hold of his stuff in the process of collecting yours because spouses often lie in the disclosure of assets. Controlling men are even worse in this regard.
2) Expectations: Try to consider what you're going to ask for with regard to property and custody. For instance, do you want to keep the marital home (buy him out), etc. Do you need temporary support? Is there property that you want out of the marital home? What type of custody do you want to pursue?
3) Custody: If you anticipate a custody battle, start keeping a calendar on how the status quo child care arrangements work now. Keep a diary on daily movements of the kids. Who takes them to school, doctors, extracurricular activites, who makes dinner, cleans, puts them to bed,etc. How often he comes to visit..what he does with them etc. Men often first say they don't want custody then suddenly pursue it and become father-of-the-year once they find out how much they can offset child support with more access.
4) (REALLY REALLY IMPORTANT) Communication: Be really really careful what you say and how you say it. I only communicate with my stbx in email, for a few reasons. 1) Keeps my anger out of it 2) I can verify he received it 3) I can take it to court. Any conversation you have can be taped and can potentially be submitted as evidence. Lay off the fighting even if you're provoked because he may provoke you on purpose to get you to say things he can use in court. Make sure you communicate about the kids so it shows that you're cooperative...be very civil in your wording. Make sure you communicate financial issues prior to it blowing up so that if it does blow up you can show in court that you warned him and he didn't respond. Try not to fight with him under any circumstances.
Bottom line...be careful, keep records, keep receipts, keep documents. Watch what you say...dont limit any reasonable access to the children. He'll be advised to do the same. Think about the well-being of your kids in everything you do. Keep a cool head, its really easy to lose your temper. And start setting up a support system with your family and friends....you're going to need all the support and help you can get.