Possible hack?

MacBook Air

I received an email that used my own email address as the sender. It quoted an old password that I had used on a website I no longer visit. The 'sender' said my MacBook Air had been hacked and I should send Bitcoin to prevent all my photos being sent to all my contacts. Although I don't care about that (no compromising photos), I am concerned that someone has got hold of a supposedly secure password.

Should I just ignore this, or maybe try to find out if there is some security breach - and, if so, how?