Statement of Agreed Facts? In Australia

I hope someone can help me. STBX and I have been seperated for 18 mths now (he had an afair for over 6 years and now lives with her) We have both reached an agreement to settle the home & business etc. He has kept the business and I have taken on the Mortgage for the family home. I paid out the remaining debt on the business loan and we thought everything was ok. He paid for legal help to serve the agreement to settle this in the Family court and i signed everything as I believe it is all as agreed. Now I have received a letter from The Family Law courts that basically says they dont think it is a fair split and we need to provide this Statement listing what we are both keeping and how we came to that agreement. I understand some would think I was silly to do this without legal assistance but its not the EX that is fighting the agreement its the COURTS. How will we do this? I still have both children living with me (20 yr old still studying no support by dad) & A 16 year old who I get paid weekly amount for support. Has anyone any ideas on what we can say to get the court to put this agreement throught as I really dont want to have to sell the house to pay him more. Infact he doesn't want more (Guilt?) Any ideas would be a great help. Thanks Linda