It seems sort of lopsided to believe in demons but not God or at least angels. We live in a dualistic world; a world of opposites.
I agree, and I love the way you chose to say "lopsided" it's just cute, and non-offensive.
As for Kurohime. Maybe this seemingly malevolent spirit in the cemetery. is following your aunt for some reason. Do you think it could somehow be the spirit attacking you at your aunt's house?. There could be a connection. Does your aunt know about your ability to see and hear spirits, and does she think her house could have a paranormal occupant? Also does she ever have mysterious scratches appear on her like you' experiences while visiting her home?
In my honest opinion I don't think you are crazy, I don't think you should seek any type of medical professional in regards to seeing and hearing spirits. Cause that is not there area of expertise.
As far as getting help with your situation, all i can say is Research, research, and more research! The more you know about this stuff the better you'll understand it, and know what to do about it.