I personally don’t believe in the whole “there is no emotion, there is peace” thing, because emotions are a natural part of us.
I wouldn’t look at your reaction as negative, Jax. You had good reason to be angry. The trick, as I see it, is not simply to prevent your emotion from ever occuring, but rather to focus that emotion into positive action. As opposed to allowing your anger to take control of you or ignoring it all together, you could, for example, direct the energy of your anger to explaining to the student that they are wasting your time, and making it clear that you won’t put up with it.
Emotions aren’t postive or negative, but what we do about them is.