However, I highly doubt she would be stupid enough to cast a bad spell on you. Anything we cast goes back to us, Threefold. So unless she's stupid and will cause herself more pain then you, then you should be Spell Free.
That only works if the witch harassing fragileone0328 is a Wiccan. And then only if she is not angry to the point she ignores those teachings. For any other witch, the 'Threefold Law' is of no notice.
Your three points are great advice, Imiko.
fragileone0328: One thing that will help is to ensure you've cleansed your own energy. Meditation and simple rituals you can probably find around this sight. Purify negative energy from yourself and it is easier to notice foreign energies. Don't worry about attempting to direct anything at her, you want to sever the connection. Keep your focus on shedding and rejecting negative energy when you preform your protection rituals.