I will also add that I read an op ed pice once on yelling at your kids that gave me comfort. The piece was a story about a woman who just lost it with her kids regarding some crayon-related incident (you can imagine a million scenarios around that topic can't you?) She yelled and did/said things she regretted and felt terrible about it. But upon reflection, she came to the realization that maybe its ok for kids to see you lose your cool once in a while. And the way she presented it I agreed with. I'm not advocating hollering at your kids all the time, but every once in a while we lose it and just maybe that is a valuable thing for kids to experience. To see and experience what it is like to push someone too far. Because reading those cues - that someone is getting annoyed or frustrated - are pretty important skills to have in the world. And sometimes we do push prople to far and those are the consequences. Doesn't feel that great, so maybe kids learn to be more sensitive and back off when mom/dad get their serious face on.
I put my money on her not even thinking about it at this point in the day. But I hear you - I've been there, I've done that, and I've felt just terrible about it. But she will survive and so will you.