Every event or conversation that upsets or displeases us is made up of two components: what actually happens in real time, and what our head does with it afterwards. We have little or no control over many of the difficult things which occur in our lives, but we can change our response to them.
A good starting point in keeping our minds from spinning out of control is to learn how to "drop the shock and awe." We do this by making a choice not to be surprised—once again—by behavior that we know from past experience is consistent with a particular person.
Because we already know what to expect, we can eliminate, or at least shorten, the time we spend trying to build a case for why we find another person's thinking, words or actions unacceptable.