completely understandable.... sorry this has happened to you. Best is to now call Airbnb immediately and plead your case, that you have extenuating circumstances and didn't know about the penalties involved with canceling. Maybe they'll reverse it for you.
Cancellations and how to contact Airbnb are the two most often repeated complaints here, maybe use the search function to learn more. In any case, do read up on what is involved with canceling. Good luck!