"You're lying to yourself" is something we've heard from our ancestors. It's an expression that was used by our grandparents before defense mechanisms became common knowledge to people other than psychologists. Everyone unknowingly uses defense mechanisms in order to cope and CDs have a lot to cope with.
So, probably mother in law was correct but she also could have been wrong. Forcing someone to face something about their self like this is kind of harsh, but sometimes it has to be done. It's like saying, "grow up"!
