Your employment of a co-host is completely separate from Airbnb's relationship with the host (in this case you are not even the host as you let the co-host set the listing up in their name). @Yanick16
Do prioritise having the listings taken down so the co-host can't accept further bookings.
Going forward do set the listing up in your name and then you can add a local co-host to listing to manage services you want them to manage.
Take your contract to a lawyer (wasn't sure what you wanted to sue your co-host for) and they will be able to advise on how you take things forward.