There are two things that always make a situation worse: Silence, and fear.

The first thing that I was taught to do in an emergency was take a deep breath, stop, and think as logically as I could. No one makes good decisions when they are afraid.

Silence is another problem that happens, either people are afraid, or dismissive, and they don't go to the police when something is wrong.

As a rule of thumb, if someone is threatening you, stalking you, or anything else that is considered a crime, you need to go down to the police station (In some places you can call it instead) and make a report.

You need to do this BEFORE the situation gets to the point when you really think police should be involved.

The reason for making a police report as soon as possible, is because in most places you need to have so many reports on someone before you can place a restraining order and important things like that.

There was a situation that my family went through, where my parents made a police report as soon as something happened, and we did not regret it. (Actually it solved our problem quite nicely....more on that later.)

So to recap, stay calm and speak up.

So don't be silent when someone is threatening you, most of the time when someone threatens your family or friends it is an idle threat. So don't let that get to you.

Always tell family and friends if you can't tell the police. Never keep possibly dangerous situations a secret! Always tell everyone who might be directly affected by the situation.

Oh, and for all that is holy and decent, do NOT withhold important information from your children or siblings (and parents in some cases)  in an attempt to protect them. That is ASKING for trouble.  You might not want to tell your children if something scary is happening, but trust me, it's better for them to be aware of it, and try to avoid it than it is for them to be in the middle of legal issues and dangerous situations without their knowledge.

Once more: Stay calm and Speak up when something bad is happening