If I was in your position my first point of call would be to a mens advocacy group. Look in the local papers, the yellow pages, or even better do an internet search. Most of these groups that I have come accross offer amazing resources to men in your position. Including legal advice and representation. The majority have a nominal joining fee - one in our area was $175, and that covered full advice, support and representation on personal, emotional, financial and legal issues. They also had the support to defer the payment while still providing help and/or offereing a payment plan to pay it off.
It's the unfortunate nature of the beast that when it comes to single parenting and custodial issues, the system is geared towards assisting mothers. I'm a single mother myself, have been since 2 weeks before the birth of my now 13 year old son. My best friend (well easiest description, not just a friend but not actually anything more that can be pigeonholed) became a single dad 18 months ago to his then 9 month old daughter. 6 months ago he also took physical (no legal docs) custoday of his 8 year old step daughter. He raised her since she was 14 months old until the split 18 months ago - and this little girl is unaware that there is no biological link between herself and 'dad'.
He has been through hell and back inside his heart and head over all this, and I have helped him as much as I can. What we found was just how biased the entire welfare, support systems, legal systems etc are towards the female becoming the single parent.
It was great to find these mens advocacy groups - they offer all sorts of support to navigate the systems and support you through what is needed to give your kids the best chance in a safe and consistant future.