I'd also be thinking about taking an AVO against this person. They are clearly working out some personal emotional crisis and you are their obsessive mind's target. An order to stay away from you and your tenants and to deal with you entirely through the EC (who can't be THAT compliant) might pull them up with a shock.
Have a look here. This Lawlink page says: “An AVO may be granted to stop or prevent behaviour amounting to stalking or intimidation, but falling short of actual physical violence.”
Even a lawyer's letter outlining what options, including an AVO, are open to you if they don't leave you alone might cool her jets. By the way, she is probably also breaking by-laws about behaviour on Common Property (if you have them).