Thanks! I gave everyone a GA.
I think my answer is most like @jca2,‘s but I also agree with most of the other answers. I use upset two ways. I use it as a reaction to a situation, but the reaction can be more tears than anger. I also use it to describe being sad. I understand using it to mean angry, but I rarely use it that way.
I remember learning somewhere that often times the underlying element of anger is being hurt or disappointed. That makes some sense to me.
My husband and I realized recently that we have been miscommunicating, because I use the word upset to mean I was disappointed and sad and just feeling badly about a circumstance, and he always interpreted upset as meaning angry. This has been 30 years of not really understanding each other when I was using the word. Maybe he learned upset as equivalent to anger in school, that I don’t know, but even native English speakers have different interpretations as seen on this thread.