They must be real threats if you are going to bother the police. She has to have threatened you with bodily harm, or you are just wasting your time.
Anyways, in my line of work, I have to be extremely careful what I say to people or I can get sued, loose my license, and even brought up on criminal charges.
I wasn't this good when I was younger, believe me I had, "no filters." I've gotten to be a lot more tactful in my old age.
How to diffuse a nasty client 101:
1. When a client gets enraged, take their side of things. Do not ask them to, "calm down and relax." Show you are just as upset, and totally agree with everything they are saying.
2. Hand the client a form designed to diffuse a situation. Companies call this piece of paper a variety of things, "complaint, customer survey, customer request, grievance." Its basically a form that asks for name, address, phone, email, a description of the problem, hand written by the customer, time to be called back, and a bunch of check-boxes about who the customer would like to speak to.
3. If you own the business, you have two options. Broken into two categories. Complaining customers on the phone, who you always need to, "call back, after you have figured out what the problem is," or complaining customers in person, who you must, "promise to get back to, later today, or tomorrow, when you have thoroughly examined the situation."
4. If you do not own the business, and are not a supervisor, then the correct way to do this is always two options, depending on phone, or in person. For the phone, "put the customer on hold, for no more than 45 seconds, and let your supervisor deal with it." For in person, "have the customer wait at the service station, while you take a moment to look for you supervisor.
5. If you are a supervisor, then as soon as you are in front of the customer, you agree with them, you take their side, become their ally, and go through the instructions of filling out, "the customer survey."
95% of the time.. This is going to be the last of it.
The other 5% of the time, lawyers are getting involved and you or your company are in boiling water.
I guess there is also, ".01% of the time, where the lunatic customer gets violent," beyond the scope of my post, imho...