Would you classify confusion as an emotion? I'm writing a short essay on emotions and I stumbled upon a few references of confusion being an emotion but no solid exclusive research results focusing on confusion as an emotion. If it isn't, what classification would it fit?

Few references: https://www.pnas.org/content/pnas/114/38/E7900.full.pdf (page E7901) which simply explains about 27 types of emotions mostly deduced from physical observations rather than neurological

And this paper, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620019/, also explains what happens neurologically when a person is confused though it's focused more on the advancement of Machine Learning: Neural Networks than pure neuroscience. This is from another unanswered question https://biology.stackexchange.com/questions/67440/neuroscience-of-confusion
Cambridge Dictionary defines confusion as "a situation in which people do not understand what is happening, what they should do or who someone or something is." This means that confusion occurs in one's thoughts, in the brain. 

I define emotion as "an irritation of the heart" or simply "a heart feeling." By heart, I mean a physical heart. Emotion is a heart response to whatever irritates it: thoughts, memories, what someone sees or hears, etc.

So, if you say that confusion is about thoughts and emotions are about heart feelings, then confusion is not an emotion. Confusion may or may not be accompanied by emotions, for example, someone does not understand what is happening (confusion) and, as a result, feels fear in the heart (emotion).

I'm not sure if I want to classify confusion, but it is a "problem with understanding," not necessary as a "condition" but as a temporary or chronic state.