The thing is
the return email is my address so no use contacting 'him', what worries me is to how he can email me from me.

The gist of it is that he supposedly has control of my system and has pictures on me viewing porn, which is crap since I only have an old XP system with no webcam!!

The guy is just a nasty piece of crap, I dare say there would be a lot of people actually paying him his money.
Should I go here?
https://haveibeenpwned.com/