How do I approach my controlling, manipulative mother about her behavior without damaging our relationship?

I am a grown woman with children of my own yet she still treats me as a child and interferes in our lives and undermines my authority on a regular basis. She is also a very sensitive, defensive person, and I hate to hurt her feelings.

She calls me daily to question me on what the kids have been doing, what I have planned for them tomorrow, and most specifically, what did I feed them. God forbid I let them have something “unhealthy”, or I will be lectured about nutrition for the next half hour. God forbid I let them watch Harry Potter or listen to rock music, or I will be lectured about the downfalls of mainstream society.

She even goes so far as to completely undermine my authority when I have set certain rules, such as letting my kids jump on her couch after I have specifically told them not to. She just smiles and says “oh it’s okay, they’re at Nana’s house now.” It makes the kids look at her like she’s a goddess and look at me like I’m the meanest mother ever. Because of this, my relationship with my oldest daughter is going downhill, and she even asked to move in with Nana.

It’s infuriating and I am becoming a very bitter, angry person because of it. I have to talk to her and make it very clear that it is important she listen and respect me as an adult, but I am terrified that she will be hurt and it will damage the good part of our relationship. I don’t know what to say to her.

Good grief that was long. Sorry. =0)