I know all too well why you're irritated. My future MIL is that exact way, but with her it's a power play. She feels she doesn't have control over her life, so she tries to control someone elses. Since we moved out, it hasn't been as bad, but there are times she'll still try to play that game.

It's something that can't be talked through (In my experience), because they think you don't know what you're talking about and since they're the older and wiser one, they're always right. Until you take her somewhere, or she sees some "professional" say the same things you have been saying for who knows how long, she won't stop.

My friend's MIL is the same way. I swear they all collaborate sometimes...