Please get this logged by the police. Its really important.
Our niece was harrassing us. She was sending txts etc (not as dramatic or awful as your incident). She was being a nightmare.
She was expecting us to act like her. To argue and go round looking for a fight.
Instead I reported everything she did to the Police. I knew there was little they could do but they did log every incident.
She pushed her luck once to often and they sent a PC round to have a word.
Shocked the bloody life out of her and she stopped.
Dont let her get away with it. You can tell the police you dont want any action taken but you want to report it incase anything else happens.