My next door neighbor downloads music illegally. Do I have to turn her in to the FBI?

Last night, I was looking into her bedroom window with my telescope and I noticed that she was using the file sharing program limewire. Now, to my knowledge, it's illegal to use limewire, not to mention morally wrong, since it hurts the music industry and struggling musicians. Should I turn her in to the FBI or the police? I don't want to ruin any chance of us ever becoming friends or getting married. Can I turn her in anonomously?