My old land lord is threatening me?

I moved into this house, and my landlady was a crack head. I payed her $110 for the 2 weeks and $300 for a month, plus $70 for utilities. She told me that international calls were free so I called my family in a different country. I also was at the Rainbow Gathering for 2 weeks, so I didn't use any utilities. I moved out of there, and she told my friend that I owe her $20 for utilities and $20 for international calls. Then, she called me and said that I owe her $100. $70 for utilities, and $20 for international calls. She also claims that I used the operator. I'm not planning to pay, because she told me that the international calls were free, and I didn't use the operator. She is also trying to charge me for utilities for the whole month, and I don't think I should pay her for half of the month, since I wasn't there. She called me from Colorado, and left me a message, and pretty much threatened me. SHe told me that if I don't pay her before the 16th, she knows where I live, and she will come and talk to me. She called me three times since then, so I thought that it's getting out of hand, so I tried calling her about 5 times and she's not picking up. She is telling me that she will see me on my door step on the 16th. What should I do? I am tired of this woman pestering me because she doesn't have any money, and is now trying to get money off of me. How did it jump from me owing her $40 to $100? Please tell me what I can do. Do you think she knows where I live or is she just threatening me? She said that my friend told her where I live, but my friend is denying it and seems to be on my side.