Tell me you have cameras and a restraining order.
If I were in your position, I think I’d have cameras facing the street, back porch and one inside. Streaming to my phone. If she’s hanging out on the property, call the cops. If she’s in the house, call 911 and report an intruder/burglar and press charges. It sounds like she hangs out there for long enough that the she’ll still be inside or on the property when the police arrive.
But seriously, this goes beyond making sure she can’t find a key. This needs police intervention.