Hacked demanding bitcoin

I received an email this morning from a domain that is hosted at Go Daddy. The domain has been dormant for a while, and I rarely use the email account. It's a side business site that I use to drum up occasional freelance. Anyway, I received an email sent from this account this morning from someone saying (in broken English) that they've hacked my site and are demanding money or they will send out embarrassing screenshots captured with this supposed Trojan virus that they've installed on my computer unless I pay them almost $900 in bitcoin. The email displays a password that I haven't used in I don't know how long and that he used it to access my contacts. I have nothing to hide as far as my web surfing, so the threat of embarrassing me means nothing. He goes on to say that in 48 hours "your device will be blocked so you cannot obstruct". I checked my site contents via FTP and don't see anything unusual. Should I be concerned?