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I'm glad you said "supposedly" Alanon, because she completely fits the description of an untreated Alanon (someone who should be working a serious alanon program, but isn't). I hope you know that alanon would never encourage anyone to tell someone else how to run their program. Her attempts to control others when her own emotional life is out of control is classic, severe codependency.
One of the things that alanon teaches is detachment with love. Codependency is every bit as much of a disease as alcoholism, and she appears to have a severe case, and may also have a personality disorder (but without an evaluation, it's hard to predict which one). Usually its the alanon who needs to detach, but in this case, its you who needs protection from her. If keeping your distance is an option, it seems the most reasonable thing to do at this point.
To diffuse her controlling, (when you can't avoid contact) you could try saying, when she tries to run your life, "You may be right" or "that's an interesting point" and change the subject. This can take the steam out of the persons argument, yet doesn't give them any power over you, because you said "may" and "interesting" which doesn't imply that you actually agree.
Here's a well-reviewed book that may give you additional tools to set boundaries with her and protect you and your mother from her manipulations. http://www.amazon.com/Controlling-People-Recognize-Understand-Control/dp/158062569X/ref=sr_1_1?s=books&ie=UTF8&qid=1323957547&sr=1-1
It can also help to pray for her. This will help diffuse the anger that's built up inside you, and put her in your mind as someone who needs help because she has no idea how sick she is. She most likely sees her attempts to control and manipulate as something she does to "help."