A.,
I TOTALLY hear you on this and only wish I had read this post sooner! My little girl went through the same thing and drove me to tears too many times. I sought others' advice and one of the best resources is the book 1-2-3 Magic. It is so worth the time to read and it's an easy read at that (I manage to squeeze in a few pages when I pee!).
My daughter started to act up right before my son was born, and the book saved me. When she started getting violent (hitting/biting me) and just mean, I had to take things a step further. I started implementing "harsher" time outs. Below is what I posted to someone else with some things added/taken away to make it fit your situation:
Having read the Supernanny books, we had tried traditional time outs in the past (with little success, since my daughter is so stubborn and refused to stay put). Because I was short on man-power, patience, and alertness right after the baby was born, out of desperation I turned her high chair into her time out seat. This meant that she'd be strapped in and I wouldn't have to repeatedly chase her to put her back. I mean really, I was already having power struggles, did I need to add another where she'd revel in the attention, albeit negaive? Yes, strapping your child in a seat sounds a bit cruel, but I couldn't continue hating my life and crying every ten minutes because she'd really hurt me physically and emotionally. When I'd strap her in, she'd resist by trying to hit/bite me, which I'd ignore and wouldn't get upset over (eventually she saw it made no reaction and gave it up, but every now and then she tries it again). Then I'd set the microwave timer for 2.5 minutes, turn the chair around so that she wouldn't have an audience (but place it far enough away from things that she couldn't reach anything), and walk away. When the timer went off, I'd return, briefly tell her "We don't hit, that hurts Mommy," ask for an apology and a hug, and let her out of the chair. We'd start from scratch then, as if it hadn't happened.
Believe me, there was a day when she was in that chair 15 times or so, but I stuck to my guns and would put her right back even if it was a minute later. That did it! Now, when I see her temper boiling and recognize that she is going to blow, I remind her "If we hit/yell/bite/etc we go in time out." She's literally had her hand raised in the air, ready to strike, and with that warning has dropped the hand, turned around, and started playing with something else!! I finally feel like I have gained back control and am not at my daughter's mercy.
Also, I was originally afraid that making her high chair her T.O. seat might make her hate it, but she is able to tell the difference and actually loves using the seat to eat. I never used the tray when she was in T.O., so that may have helped. She also has a booster seat at the table, and likes picking which one to use for meals.
Truly and honestly, my little girl is back to her old self and the storm has passed. It took about 2-3 days for her to realize that I was CONSISTENT with the time outs, and that dramatically reduced her outbursts. After a week, I had my great kid back!
The irony in all of this is that I taught elementary school for 9 years (grades 3-5) and had control of 20+ kids in my classroom. I had them treating me respectfully and they never dared rock the boat. To think that this two year old was giving me a run for my money when a *mass* of older, more cunning children couldn't really blew my mind. But then I reminded myself of the term "terrible" twos, and how people equate toddlers' mood swings and irrationality with that of a teenagers, and I was less hard on myself :)
Be consistent, try hard not to show your fear and tears (they love a reaction and think they've won!!), and stick to it without batting an eyelash. Yes, it will be hard for a few days but I promise you you'll gain back the power and that nice little girl. You are not alone in the mayhem and chaos, I promise! As Gloria Gaynor so aptly put it, "I will survive!!"
L. :)