I'm wondering exactly what constitutes emotional abuse?

It is not an exact: Science. There are varying degrees of emotional abuse from teasing, to intimidation, to bullying, to badgering, and name calling. Neglect can be emotionally abusive. Exposure to parents fighting or seeing a parent physically abuse a sibling or parent can be as well.

Eval: Get a full psychiatric evaluation to determine what bothers you, and consider medication to take the edge off them symptoms. Next, get a referral to a reputable psychotherapist to discuss what your current emotional state and life experiences mean to YOU, including emotional abuse. Meds and therapy together are the most optimal approach, for the most part.