Amazing how much energy there is here about child abuse. Most of us have experienced it in some way, either directly or as a witness.
I know a lot more about empathy than I do football. Here's another way to think about it when it runs amok, as an alternative to "too much."
Empathy is made up of two parts: sensitivity to emotions in others , and intelligence about what to do with that data. The behavior that
@KontradictioN speaks to comes from sensitivity being much more developed than the intelligence. Those people get overwhelmed by the data they are taking in, and the data is often about pain or discomfort others are feelings.
And, the balancing capability to empathy is assertiveness (sensitivity to and care for the self). "Overly empathetic" people often have an underdeveloped sense of self and ability to be assertive.
So in sum, when someone is overly sensitive, doesn't know what to do with all that emotional data about someone else, and doesn't have an equally strong sense of self, they get weird (technical term).