@Carrie334
I'm sorry you have had this awful experience.
@Helen3 has offered lots of sage advice. I see you already have a co host. Did he check these guests in?
Your listing looks lovely and I can see you've worded it to make it attractive to people wanting to get away form it all. Unfortunately this also makes it very attractive to guests you dont' want.
It's easy to be wise in hindsight, but here are quite a few things that make your place very attractive to people who plan to do the wrong thing IMO.
Specifically these are - self check in, combined with no disclosed security/surveillance combined with no stipulated security deposit combined with no personalised house rules.
For guests planning to party - they see your listing, which looks kind of remote from the pics, there's self check in so likely no one about to monitor them, it's gated so they can get up to mischief in privacy, the house is spacious so it will hold plenty of partyers, there are "grounds" to spill out on, there's no surveillance to "prove" there were extra guests and there's no bond if there is damage. And there's no house rules apart from the few generic ticked ones, so they figure you're a bit of a pushover. This is a great place to have a rave!
The bond/security deposit is actually pretty useless, but so far most southern hemisphere guests haven't realised this, so it's quite good bluff value.
I hope I don't sound like I"m criticising, just trying to point out how appealing your place is if I'm planning a really large party.
IN your house rules you may find it helpful to say something like "The number of guests booked for is the MAXIMUM number of guests allowed. If you booked for 2 guests, only 2 guests may stay. This includes "visitors" This is an INSURANCE REQUIREMENT. Our insurance also requires that you enter the FULL LEGAL names of every guest, including children to the section of your booking "who's coming / invite other guests' section. Violation of this rule will result in immediate cancellation.
IF I were you I would study the listings of more experienced hosts with large houses ( doesn't have to be in your area) and see how they worded things in their description and their house rules. If you want to enforce something it's best it's in house rules, but it doesn't hurt if it's also in the description.
I would spend some considerable time on this and then go around to the neighbours, eating humble pie like mad and explain the plethora or strategies you now have in place to ensure this is most unlikely to reoccur
Good luck!