Make sure all the messages are kept, photographed, printed etc so that there is a record. Next see a solicitor to write to her warning her off. If she persists and action for nuisance or harassment can be taken. There is no way she'll be able to succeed in doing what she threatens of course but you can take steps to silence her in this way. Happy to discuss further. I hope that helps. Please leave a positive rating so that I am credited for my time.