This makes me curious. What was said that made her fear for her safety? Was her exit blocked? Was she physically threatened?
I can't imagine anything that would ever lead me to call the police to deal with my husband. Then again my husband has never so much as raised his voice at me in the 10+ years we have been married. If he was aggressive by nature, was prone to male posturing and I had seen him fly off the handle and do stupid shit in anger, then I might have a different view.
Not accusing you or even defending her actions but the old addage "don't shit where you eat" might apply here.
In my opinion, three kinds of people always give you signs: the crazy, the predator, and the disloyal. When the actions of others take you by surprise, looking back usually reveals "signs" that the behavior was possible - if not inevitable.
Sorry 'bout all the chaos. Hopefully life will calm down soon and you can get on with moving on.