I'm very sorry about your situation, but you know what? You will be fine with or without him. He's the loser in all of this.
I would stand my ground and not give an inch when it comes to support for your children. Shame on him!
I do hope that you are okay and will have a good weekend. The stress of what he's done would be enough to drive you nuts, but you are far more stronger than you think.
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.