I would get a lawyer involved. Hopefully nothing will come of this, but having a lawyer, is a good idea. Listening to their advice after retaining them is even more important. Dealing with CPS is not like fighting a case where you're trying to prove the other side wrong, it's about addressing their concerns.
This answer is provided for general purposes only. If you need legal assistance you should consult with an attorney. Responding to questions DOES NOT create an attorney-client relationship.