Ballet, first off you need to run a full virus scan as it looks like you’ve got something on your PC.
Trying to login to FB and getting that message – FB wouldn’t generate it, it’s coming from whatever virus is on your system.
The email is BOGUS unless it’s addressed to you by name (not ‘user’ or your email address or something along those lines), so delete it and DON’T follow any link within.
Most important thing is a full system scan for viruses. Please let us know how you get on.