@Jorge499 If the guest wrote in a message that if you charged her for bringing 15 people when she booked for 8, she'd leave a bad review, that's extortion and against Airbnb TOS. Contact Airbnb, tell them what happened, and ask them to look at the guest's message to verify that she is attempting to extort you, in which case they will hopefully block her from leaving a review or remove it if she does. I hope when you say "message", you mean an Airbnb message, not a text.
And if you do leave a review, just be factual- the guest arrived with almost twice as many people than she booked for, said she'd deal with paying for them in the morning, then skipped out without paying. Don't mention the extortion or any Airbnb involvement in the case, as that could cause them to remove your review.