My mother drives me crazy.

Seriously she is like Monica's Mom in friends. She pick at everything I say and do, she demands stuff not 'may I borrow' totally rewrites history and is so effing passive aggressive regarding everything. She so pushes my buttons, she just spend an hour here and all I want to do is eat or smoke. Aaaaaarrrrrrrggggggghhhhhh I am going to think of random objects and cover myself in the golden light, she can't help it I suppose. Beeeeee calm. Beeeeeee calm and deep breaths, beeee calm.

That sounds like a combination of my mom and dad.
Mom in the nitpicking sense, and my dad is captain of the passive aggressive team.
The most you can do is take deep breaths, though.
I'm here if you want someone to talk to personally.

Treat her like a kid and distract her? Ask her about her life when she was your age, get some stories out of her about growing up. When I did that with my mom I understood her a bit better and could identify with her problems and feel sorry for her growing up.

My Mom is one of my biggest sources of anxiety as well. I'm slowly learning how to deal with it in a more healthy manner, but it's hard to break habits of a lifetime.

I am another who struggles with my mother. She has a strange mix of helplessness and hyper criticism. Consequently, I have taken over the mothering role in my family and am working hard to no longer allow or engage in this. And (Wouldn't you guess-I am very hyper critical of myself). It is hard. I recently listened to a great CD by Dr. Clarissa Pinkola Estes, It is titled "Warming the Stone Child" . She is a story teller. One story in particular talks about the experience of the "un-mothered child". It spoke very directly about attachment and the experience of feeling like/or being a abandoned child. If you haven't heard of it you might check it out. It brought me good perspective.