What can I do to stop  my neighbor from harassing me?

First, speak with the neighbor, if you haven't already; see if you can work it out between yourselves.

Second, if that doesn't work, go to your police. You don't need to file a formal complaint or press charges; however, you should speak to the police for three reasons (in a very calm, reasonable, "how can I make this better" sort of way):

1) The police probably have a great deal of experience with situations like this; they can most likely offer good advice

2) The police may be able to speak to your neighbor on your behalf and get her to understand that she needs to stop

3) If matters escalate to where you need to file a complaint or press charges--or your neighbor attemps to blame you for something--you'll have already created a "paper trail" that there is a problem but you are doing your best to resolve it amicably.

I've taken my own advice, btw--it helped in a dispute between our neighbors and ourselves.

Good luck.