meaning of dreams fear of being alone

Hi i`m 16 and a high school student. My fears are being alone and sometimes the dark. My relationships are with friends in school, ex boyfriend and mom and brother.I have been having nightmares, Each different yet same: Large number of people or myselff get killed in different ways. My dreams haven been like this for the past year. One that I can remember clearly is I was a servant to a noblewoman in europe. Her husband cheated on her for another woman and slowly went insane until one day she snapped and killed her husband with clippers. I tried to stop her but she tried to kill me. Her eyes were bloodshot and her smile was manaical. It was an horrible and scary expression An eye witness knocked her out. Another servant screamed and then she gave me the same expression my mistress gave me. What does this mean? And why do I have only dreams where people die?