daring, I'm very sorry to hear this. Divorce from crisis people is never easy and it can be down right ugly. I'm not surprised he came back and wanted spousal support. Why should you be paying all of the IRS bs as well? Can I assume he was in the middle of that mess too? Then he's responsible for half of that if his name was on the tax papers.
I hope that you have a good lawyer who will fight for you and your kids because this man has been talking to someone and they've filled his head with sugar plums full of bs.
daring, divorce is ugly and you can't be friends w/them when you are discussing assets and division of property. Unfortunately, he is now the enemy and you will need to stand your ground and get tough. Get angry, let it out and keep your business hat on.
Good luck! Again, I am sorry to hear that he's going down this road.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.