Hell hath no fury like a woman scorned.
This reminds me of a friend of mine who is going through a divorse. His grandparents house was given to him upon their death. She now has his house, she is living there with her new partner and new child. This is wrong wrong wrong. He is living in his parents house and struggling with a new job. As if that wasn't enough, she is hell bent on making his life a nightmare, refuses to let him see the kids, dragging him through court. She also wants money he doesn't have as well as the shirt of his back. I would implore you to take into consideration that if, and only if you need money to get by and not for luxuries then talk to him. He needs to survive too. If you pursue him for all he has left I can almost guarantee you it will turn very nasty.
I have a child with a girl which wasnt planned and we talk and work things out ourselves. Other women exploit the system which render the guys in Ireland subserviant to their greed for as long as they can. The kids are used and become the real victims. As the recession hits a peak you will see more and more Brazilian style divorses. My honest opinion, try be reasonable and talk to each other. I would seriously pop a serious fuse if the girl that I share a baby with had her eye on my life savings as well as my home. The barking dog normally gets the bone. Talk! I'm sure if he loves his kids he will make some contribution. Careful not to make any outrages demands, open the the table for discussion. If that does not work then talk to a solicitor but tell him your doing it for both your childrens necessity and not pure bigotry or greed.
Good Luck