Surprised nobody mentioned the mediation process...
Like Nakkers, I opted out of the assets, took all the debts, and after a single meeting with her lawyer, started the child support stuff immediately. The numbers are very easy to calculate. Alimony is a different animal, as are "special" costs relating to children, and her ability to earn.
In a nutshell though, and my case was very unique but I will say this: No matter how hard, always do your best to negotiate, and maintain civility for the children. The money doesn't mean **** when it comes down to it. Obviously it sounds like legal advice is your number one priority right now, and as others have said, be prepared to cough up support payments over the previous time. Another big thing to remember is that the court will advocate for children on every level, including their right to see the parents. Don't give them a reason not to.
Incidentally, I'm a single Dad to a pretty damn awesome autistic lad, 5 years into my separation. My final divorce papers are now complete, with no custody order and no contest for anything else. And I never once darkened the door of a court or a lawyers office. Never missed a payment, and even now with the court reviewing the final portion of this, I was overpaying a bit. Opting not to "fight" likely saved me 50 grand in legal battles, not to mention the soul-crushing reality of living through huge stress. We get along better now than when married, lol