Never ever do that again. Never. To her, or to any other dog.

I do not blame her for being wary of you. Hitting a dog (or a helpless child) does not solve anything, and often creates larger problems.

How could we not be upset?

Promise you will never do that again, and take her for a nice, long walk, or whatever her other favorite activity is, do that.

I am not mad at you, I have however lost respect for you.