If we follow our train of thought, it soon becomes apparent that emotions are only moral to the extent that they reflect human intention. I once heard someone put it this way, "Emotions are neither good nor bad. They just are." To the extent that emotions are a kind of automated response to what happens in the world--or even often caused by the chemistry of our bodies--they are not a matter of intention or choice. Therefore, to that degree they cannot be evil.
Now, we need to be very careful here, because sometimes emotions do involve intent and thus come into the sphere of morality. This is certainly the case when it comes to what we do with our emotions. Ephesians 4:26 is an excellent picture of this truth: "In your anger, do not sin." It is thus possible to be angry and yet not sin--that is, not wrong others or do wrong. However, one can also "give way" to your anger and commit horrible crimes.
John Wesley (1703-91) also had a category for a kind of sin that happened in a moment of emotion. You did not intend to lose your cool and yell at your children in a moment of uncontrolled anger, but you have been overworking and skipped lunch. He called such sins, somewhat humorously, "sins of surprise." We can wrong others in such emotional moments. They are not pre-meditated actions, and so are less "moral" in nature than many other actions.
But they may involve choices we have made in the past. Did we have to go into work at 5am this morning or did we have to stay up so late working? Have we unnecessarily let work take too large a role in our lives? Could we have chosen to eat more healthily or did we have to skip lunch? These sorts of choices are not as heavily "moral" as some others because they do not involve significant intent to do wrong. But because they involve our choices, they do come into the realm of the moral. This is especially the case the more we know we have a problem in certain situations and yet continue to put ourselves in them.
Once again, our claim is that evil always involves intent to do wrong or to wrong others. Morality is a matter of choices. There is no such thing as unintentional or accidental evil. Evil is a matter of moral choice. Accordingly, emotions are not good or evil in themselves. It is what we do with them that brings them into the sphere of morality, as well as how our choices have led up to them. If we know we lose our temper in certain situations, then to put ourselves in those situations is to do evil of varying intensity.