Your friend Sandi, however impolitic, was right.
You did just "have to deal" with her that day. You did not have to be nice to her, you did not have to talk to her, you did not have to avoid her or do any other one specific thing. Rather, you had to adjust all of the actions you would have performed anyway around the difficulties that her mood presented. You chose one way to "deal" with her. Your colleagues may have chosen a different way. No matter what course of action each of you took, she stood in your path like a rock jutting up in the path of a stream. And you were bothered by the incident, which is to say that it affected you despite your attempts to thwart it.
No, it's not fair. Even if you were the sort of person who wallows in "niceness" and good cheer every minute of every day of your life, it still would not be fair to put that sort of a strain on your emotional resources. And let's face it, humans are not rocks. They can choose whether or not to put us in that situation. So what are we to do?
Aside from the typical psychological drivel about not being defined by the situation, of course.
I say, go with the rock theory. Sandi is a rock in the path of your psychological stream. Chop at her with a big hammer.
You still lose, though, because you still had to "deal" with her.