Unfortunately, I know how you feel.
I've taken Kito to Petco a few times, but I always hesitate before I do--he's not to fond of children either. He is just unpredictable.
Last year I had a horrilbe scare when he bit the neighbor's little girl--she came running at us screaming "can I pet your dog?", and we were in my driveway on our way inside from a walk, and he was leashed--she got too close, and he nipped her. The whole time, I was yelling at her telling her "NO", but she didn't listen. Thing is, all of the kids on the street know that the little red dog is the "mean one" Rather than explain it, I just told them all that, to avoid such situations.
Thankfully, it was just a little mark on her thumb, and her parents were very cool about it, but I was so scared. Her mom even asked if I wanted to use her to help Kito get used to kids more--I thought that was nice, but unneccesary. He's gotten a lot better, and if he's inside, and not leashed, and they don't run towards him, he is good with them.

I'm sorry that you and Tasha had that bad experience. Please give her and Tommy both a big hug and kiss from me