What happened it's awful, I tried to search them to block them but both their accounts where already gone on FA. Hopefully he never come back.
I wanted to add a little suggestion, I hope you don't mind it ;;! But adding a "Work in Progress -artist username- Do not use/steal" could be useful! I do that to the WIPs I sent, in big ass fonts more than once in "shade" with 20% opacity.
Also thanks a lot for sharing your experience, my wife draws a lot of men from time to time so knowing these characters are from a scammer is useful. (tho she and I always ask 100% payment upfront, but it's still good to know!)