I sympathize with your problem. I am guilty of this, too. I am really struggling with the make-up part of argumants with my 4.5 yo DS. He is very sensitive and emotional and really a sweet guy. He will always apologize, forgive, hug it out...even with all that I constantly hear myself rubbing it in, AFTER the nice make-up. I talk too much. I just need to know when to shut up already. I'm workin on it, as you are. Know what? The realization is half the battle. The fact that you care enough to admit your wrongs means you WILL succeed in getting past this.
My thoughts are this: apologize. Admit it when you catch yourself shaming. She will be more honest if you are. Also, positivity. Give her major praise for doing well.
It often helps me to look at my younger child, i see her at a more helpless stage and cant imagine saying these hurtful, unneccessary things to her. Hang a picture, if there isnt one already there, on your fridge of her just days old. Go look at it often. I find it helps me come back to a place of personal responsisbility. I realize my son needs me to be the adult.
Also, best book, EVER--Kids are worth it. If you haven't read it, get it.
oh, and also, hugs to you, i hope tomorrow is better.