I've known this girl for a while, this girl told me before that she has feelings for me before but I'm not interested. I rejected politely and tell her to move on. After a while then she started to push me with all kinds of stuff like I really need you, try to forget you but can't, and you name it like other love related stuff. Then she started to dig information about me like my private stuff that she shouldn't know about. This is the part that I feel that she's over the limit. I mean, this is not the right way to know a person and to really know a person is by talking/communicate/chit-chat with him/her. She took the back door instead of the front door. I'm so pissed until now that she won't stop disturbing me, I scolded her and told her to just leave me alone but she just don't understand. 

So any advice on how to handle this type of people? Thank you folks a lot!