@Linda100 That review definitely stands out like a sore thumb and the fact that he/she wrote it in all caps just makes it look more unhinged. No prospective guests are going to take this seriously amidst all your other great reviews and your response was professional, and makes what went down here quite clear. Whatever she wrote in private feedback, while it understandably was upsetting, isn't visible to anyone else, so I'd just try to put it out of your mind- there's nasty crazy people out there and it's best to give what they say or do as little thought and energy as possible.
I do hope you flagged them.