This post made me cringe because I've had many near misses with losing work like that. To hear that it actually happened to you... ug.

A few times I recovered my work in Chrome with

Control Shift T

This brings back a closed tab. However, I'm guessing that wouldn't have worked for you. Honestly, sometimes when I've spent a lot of time on something I've straight up copy/paste/saved it into notepad because I was so paranoid about losing it.