Is this an invasion of privacy/against the law?

[Jay]

If you put stuff into the public domain then don't be surprised when people read and comment on it afterwards. You might just as well be printing it out and pinning it to the local Town hall noticeboard.

Either make your status on Faceache private or don't conduct your private life in an open manner.

If they are reading private messages between you are your bf then ask them to stop and respect your privacy or don't leave your FB account open so they can read your messages.