Crying mother of a screaming 2 year old (or vice versa)

I am about sick and tired of the 2 year old fits. They make me want to cry. My daughter is a doll, a charmer, a I-get-what-I-want-because-I-am-just-so-cute kinda kid. 99% of the time, she is sweet, funny, compliant, COMPLIANT. That 1% though, is enough to make me want to run away from home, with only the clothes on my back and a case of liquor.
I have never been a patient person. I remember when I was 12 and my brother was 2. I wanted to rip my hair out when we went out to restaurants and he did the kicking and screaming thing. He would arch his back as my dad was trying to put him in a highchair, which pissed off my dad, which set my mom on edge, which made my 'Gotta be the mediator' gene swing into action, and it.was.just.so.tiring.
I swore to myself that when I had a child, he/she would be GOOD, would NOT kick and scream and cry in public, making me look like a deer in headlights who wants to be run over. But, did that happen? Oh hell no. It was only a matter of time before karma bit me in my ass, seeing as I was an angel for most everyone, but knew how to say 'Aw, shit' in front of my grandparents at just the (im)perfect time. So. Here I am.
Grace wanted Spite (sprite) tonight with dinner. She is on a sprite spree lately, and I am constantly worrying about her cute little teeth, since mine were horrendous. (You know, the whole 'I want my child to have better than I did' thing) So, I convinced her that she should have milk, and even drank a small glass to show her that it wouldn't kill her. Later, after dinner, she informed me, matter-of-factly, (everything she says has a bossy air to it) 'I HAVE SODA'. She then proceeded to go into the pantry and bring out a 2 liter of Dr. Pepper. I not-so-calmly told her she couldn't have soda 30 minutes before bed; so sorry. Guess I should not have thrown in the smart ass 'so sorry', because that just set her off.
Grace: 'IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII HHHHHHHHHHHHHHHHHhaaaaaaavvvveeeee S.O.D.A.!!!'
Me: 'No baby, not at night'.
Grace: 'MYYYYYYYYY soda!'
Me: 'No grace'. (gritting teeth already)
Grace: 'I hab (have) it!'
Me: 'For the love of Pete, you CANNOT have soda at 8 o'clock at night! So sorry! Give it up!' (by this time my blood pressure is up, & I am a bundle of bunched nerves)

This is where she falls to the ground like she has been struck, thumps her head on the pretty wood floor, and proceeds to scream at the top of her lungs. I'm sure the neighbors appreciated that. And she cries real tears. And sweats, and shakes, and beats her fists on the floor, and throws the 2 liter at me. And then:

'I want my daddy! '

And this is where I silently walk out of the room, and say under my breath, 'Oh, he can have your little fancy pants sassy ass!'

Someone, tell me again, why do we choose to have offspring???