In general, a relationship is emotionally abusive when there is a consistent pattern of abusive words and bullying behaviours that wear down a person's self-esteem and undermine their mental health.
There are several red flags of emotional abuse. Keep in mind that even if your partner, parent (step), co-worker, or friend only does a handful of these things versus doing them all, your relationship with them is still emotionally abusive.
Teach your children that relationships are based on respect. Don't tell them that sometimes adults argue. Raise them to be kind and be strong enough to walk away from toxic situations.
ALWAYS BE KIND.