The word "psychopath" gets thrown around a great deal and everyone has nifty and handy dandy little mental health labels they like to sling on people who have royally screwed them over in relationships.
We always hear the following:
He/she has Borderline Personality Disorder
He/she has Narcissistic Personality Disorder
He/she has Cluster B Personality
He/she is a manic depressive sociopath
And on and on...
While I don't claim to be a psychologist, much less an armchair psychologist like those who want to prescribe crappy people with crappy personalities they've had the misfortune of being involved with–with pathological mental health issues–I am quite familiar with psychopathy as it's been a subject that's always fascinated me.