You might like this book, it's called Memoirs of a baby stealer, lesson's I've learned as a foster mother.
by Mary Callahan. It sounds like what you are experiencing right now.
Apparently it must be extremely common in this country (big surprise, right?).
Also this seems to be a great website on CPS
and their evil ways. Not sure if you have seen it? There are legal documents and also tips on winning cases. They also have a chat room (on the left, down the page a bit) and message board. Maybe you can get some good tips, at the very least you can maybe find some support from others who are going thru similar experiences.
I am so sorry you and your dc are going through this, I can't imagine how you both feel having to deal with this insanity. I hope maybe these links can help, as well as the lawyers. Why can't that worker be grilled in a courtroom...a good lawyer can turn a liar into a quivering weeping jellyfish (yeah, I know jellyfish can't cry, they don't have eyeballs). Perjury is a crime, isn't it....
Just hang in there, go to the top of the mountain and confront those 'people'. They are dark forces that you must do battle with. Be strong. You can drive them back under their rocks.
Sometimes when you look at the world, you see people who get everything easily and don't appreciate it. They have all the money, power, etc and don't act like decent people. There is some lesson here, but it's hard to figure out why these things happen. Sometimes the nicer a person is, the worse things go on. It's how you can deal with the problems is what counts. Don't let them beat you down, focus on appealing your case. God, I hope something works out for you and your dc.
Please keep us updated, pm me if you would like to anytime! I'll try to help with whatever I can.