You should file for custody immediately in order to get the courts involved. Even if you obtain a visitation order it would make it extremely difficult for her to soirit your child out of the country without your permission. Good luck.
You should certainly have an attorney for DWI cases as the ramifications could be serious. You should not be posting facts about any criminal case on the internet as it will serve no useful purpose. I suggest consulting with a local criminal defense attorney and saving any conversation for a face to face meeting. If you are unable to afford counsel, it is possible the court will appoint one to represent you.
The use of statements would be determined shortly before trial. One should not speak to federal law enforcement without counsel as lying to a federal law enforcement official is a felony. If you cannot afford an attorney then the agents will help you get representation. Good luck.