Block. If you can’t block, ignore. I’m fully prepared to accept that someone has video footage of me threatening violence (mostly against bad programming practise), but not of anything pornographic (well, ok. Maybe in black and white in a tasteful arthouse style…):
[…] Given how many details about me it got wrong, the perp obviously knows almost nothing about me — other than my email address. I suspect they got that from the Ashley Madison hack, which I’ve written about before.
I got a number of sextortion threats from that hack and ignored all with zero consequences. You can safely do the same.