Psychopathically tells you how someone acts: in the manner people link with a psychopath — coldly, without real pity, sometimes with a smile that does not match the harm. It is the adverb from psychopathic. You will almost only see it in writing about crime, film, or psychology. Nobody at the night market needs it. Though actually, if you only mean “in a wild or mad way,” this is the wrong word; that looser idea is closer to crazily or, in a medical sense, during psychosis. Psychopathically is narrower: the harm feels empty of normal human feeling.