I had one of these emails last week too. I was angry not upset. They demanded £1900 - ha ha ha ha ha!! I thought - who the hell would care if I was looking at porn? I don't work, my OH doesn't work, so who would care?? As I know I haven't been watching porn, and have no intention of giving anyone any money, I blocked the email, changed my email password, and also changed the password on my broadband router - my techie son had to talk me through this, as I had no idea the router had a password :-)
Don't worry about it. Don't get frightened. Don't give in. Change your passwords, block the email and hope they fall under a bus next time they go out.