Is there a medical reason when someone exhibits jealousy of others, lashes out to blame others for their problems, can be very kind and caring but can then become nasty and hateful, pretend they are so tough and that everyone is afraid of them but at the same time very unhappy with their life but tries to pretend they are happy go lucky, can be very mean, cruel and insultful at times
Degree understand your concerns went through your details. I suggest you not to worry much.  From the description you gave, I have every reason to believe that the person you are describing could be troubled with paranoid personality disorder of paranoid schizophrenia. I request you to consult a psychologist / psychiatrist with this person for diagnosis and treatment. Psychotherapy techniques should suit your requirement. If you require more of my help in this aspect, Please post a direct question to me in this URL. http