OCSP stapling and Certificate Transparency logs seem to provide a pretty good defense against man-in-the-middle attacks if I discover that my private key has been stolen. I can revoke my old certificate and switch to a new one, and clients should be aware of the revocation.
However, what if I don't know that my private key has been compromised? Are there any measures for detecting if my key is being used by an unauthorized party? Or ways to defend against MITM in such a scenario?