Hello @Eric895
Get in the phone asap to air bnb and explain your situation.
Do not accept or Tick any request agreeing to a refund ( you lose everything)
To avoid a lengthy resolution process etc etc...make it clearly known to the air bnb operator that you will NOT be messaging the guest and that you please want air bnb to deal and correspond with the guest directly themselves.
Without delay Tell air bnb in the phone you are generously willing to offer a 50% refund despite your strict cancellation fee.
This leaves the guest with the tempting generous offer made by you as the host of a 50% refund which is quickly accepted by both parties as 50% is better than nothing.
Good luck