speechless

this happened in my house, in my kitchen to be exact yesterday while georgia and i were 'discussing' her beverage choices. she is the ONLY person in the world i have met thus far that leaves me speechless, recklessly grabbing for words that are simply not there. im dumbfounded and frustrated at best. and a little pissed and fed up at worst. the dialogue went like this:

gk: mommy, may i have some milk please?
me: no, sweetie, your tummy was upset this morning, so we are going to stick with water for the afternoon.
gk: but why?? i really want my milk. just a little glass, please...
me: no. not today. your choice is water or nothing. milk is not good for an upset tummy.
gk: YES it is...it will make me STRONG...you said that, remember?
me: yes, i remember, but we are not going to discuss this any further. water or nothing. please stop arguing with mommy.
gk: im not arguing.
me: yes you are.
gk: no im not.
me: yes, georgia, you are and its disrespectful.
gk: no im not being disrespectful.
me: STOP it right now. (i typically change my tone, but rarely my volume. with the sudden change in volume...i got results...just not the ones i was hoping for)
gk: (real tears...and a look of horror on her face) mommy...you, you just yelled at me.
silence....
me: georgia, im sorry i yelled. its not okay to yell like that in our home. honey, please forgive me and lets try really hard to be respectful and not argue with mommy. okay?
gk: its okay mama. we'll try harder....and im only just a little disappointed in you.

so there i was speechless. stupid. without words or a comeback. seriously, at that moment i was just thankful i use words like 'disappointed' and not 'failure' because that would have really left me feeling like junk. i dont know what to do about my 3 year old trying to parent me. im at a loss as usual with this one and would love any suggestions.