where does THAT VOICE come from?

So the kids, as usual stuffed about with their dinner last night. And after endless badgering, encouraging, pleading and begging - I snapped. "Just eat it!" in the most mean horrible roar I could muster. When the nearly 6 year old stormed off I said "you will eat those peas my friend" in the most threatening tone. And the barely audible whisper from the couch was "no I won't". So he was removed from the couch by one arm, ordered onto the stool in the kitchen and told "this is the moment when you realise that you will eat these peas....now!" And he did : 5 or six spoonfuls in a row. And Little Miss just turned 3, who likes peas, was given the same riot act about her carrots. "You eat them now" and she did - painstaking orange disk after painstaking orange disk. But at what cost? I had completely done my banana! There must have been a vein popping out of my temple, beetroot face and bulging eyes. Sure I won. But what is it with kids that they just WILL NOT LISTEN to 500 nicely worded, rational, logical, 'for the best' requests but will jump when the psycho-mummy appears? How the hell, as a responsible parent, can you really put up with the level of disrepect that is continual adamant oblivion to your effort and pleading. I know I am teaching my kids to react out of fear. I know this is not good for any of us. I apologise for yelling at them. I reinforce they need to do what mummy asks first time. I sound frighteningly like my mother, or worse still like my father.

How do you hold your ground, reinforce your values and stay sane? Anyone, anyone??
I have given up asking God to give me patience - He just won't do it fast enough.