Go to DA and let them hear the messages and transcribe it for you. Charge her with harassment first degree and ask for her permanent incarceration. First,however, go to a therapist and act nervous and tell them you've had trouble sleeping and nausea because of the threatening calls. Let the therapist hear the Calls. Also do this with your medical doctor.
Then, after a few weeks, file civil charges for monetary damages for the amount for 50 thousand dollars against her for personal injury. Keep going to therapy once a week, even to a cheap licensed one in a church with a certified sociaal worker, who can later write a report about you nervousness and sleepless and worries and fear. Same with the MD. it Will fix her for Good! Make sure the THIS is added to the DA charges. They will go after her in court big time.