What do you do when you have a really crazy, possessive friend?

I have a friend who acts like Penelope Cruz in the movie "blow." lol. Ok its really not funny cus she's seriously a hot headed, slightly psychotic, obsessive friend. Im afraid the more I ignore her the more crazy she will get :'( what should I do? Luckily she doesn't know exactly where I live. But she does know the street!