I might be a psychopath
Have you been diagnosed as a psychopath?
No, but I feel like I have those characteristics of a psychopath.
I understand your feelings.  It is always best to get properly diagnosed by a professional.
Well, what does it mean if I have already killed someone?
If you have killed someone you should turn your self in and make a confession. They can also diagnose you while in custody and get you the mental help you need.