What to do?

[FatherTime]

You can go directly to the DA's office.  Take the copies of the state laws that apply and any supporting documentation and names and addresses of any witnesses.  In some states threats of bodily harm is classified as terrorists threats, such as California.  Going directly to the DA is faster than waiting for the police to act, and it may never go any further than a police report.  The DA's office can act more swiftly.  

[norma]

There is absolutely no doubt that you should explain to the court that this woman has threaten both yourself and the child. She is unfit to have custody when exhibiting such irrational behavior. You should file for primary custody of the child to get her out of harms way. Remember, it is EXTREMELY important ABSOLUTELY IMPERATIVE that you remain very calm, cool and collected when speaking in court. Let your ex throw a fit and go into a rage but YOU MUST remain calm. The judge will see who is unfit. It would be perfect if you got some of her threats on tape . . .
it's all in the proof really.