Is it "empathic" or "empathetic?"?

According to the dictionary, the terms are interchangeable. One I checked even gave the identical (word for word) definition for both.  I am not aware of there being a British versus American usage difference.  Most dictionaries indicate that empathetic is a valid variant to empathic (or the reverse). Consider the similar words apathetic, pathetic, and sympathetic that are based on the -path- (pathos from Greek) root.  these forms suggest to me that the "proper" version ought to use the -etic suffix.

The word is a turn of the century (1900) invention (came to exist to describe a psychological attribute during the developmental years of modern Psychology).

While not familiar with empathic and question if that is a legitimate word, empathetic is well known, meaning exhibiting empathy.

Two different words with different meanings. Both are correct in the right context. Look them up. 

Empathetic is correct for most circumstances.

Empathic is like psychic but with feelings instead of thoughts. Like Betazoids in Star Trek.

Empathetic.