I'm glad that you shared that, cause I sometimes wonder if I'm the only one who often resents the codie more than the alcoholic in my life... my former AH's girlfriend is a class A codependent/high dominance person, and right now I see her as one of God's children worthy of having duct tape placed across her mouth, which she cannot keep shut. She drives me up the wall with her sanctimonious interference in my daughter's life-- and the concept of backing off is completely alien to her. Sound familiar?
Deep breath: remember, no matter how warped and controlling your MIL's behavior is, somewhere way under there is the expression of affection; I kinda think it's better to love in a damaged way than to not care. And, I hope for your sake that she lives a long ways off.