

It’s just a mistake, there’s no point in beating yourself up over it at all.
Try to find a way to laugh it off and either cancel or have a fun time doing something else in the area.
Your mistake is an embarrassing inconvenience. Nobody is hurt, nobody lost their job, you aren’t fired, evicted, or divorced.
Take a deep breath. Self-forgiveness is a skill worth practicing, lest you poison your memories with regret.
Fax machines!
They were invented long before the computer or modem, with the original patent being issued in 1843.
They seem wildly outdated, but the ability to replicate the signature (iirc) led to faxes being accepted as legal documents.
This speaks more to the underlying usefulness in earlier eras, but it’s still wild to make a phone call that leads to a printed document.