How can I protect myself and my family from a false Wiccan out to harm me?

I know that Wicca is usually only used for good, but I believe the person in question is not a true Wiccan. I am not an easily impressionable person, and I have a steady heart and mind, but I have good reason to believe that this person has tried to harm me and my family, and has taught at least 1 other person to do the same using incantations and Magick. I am not a Wiccan myself, although I have a little knowledge of the belief system and definitely have an open mind and heart and respect for the beliefs of others. Are there any true Wiccans who can tell me how to protect myself and my family from someone who calls themselves "Wiccan" and is out to harm me? This is not a joke and I would be grateful of any genuine, constructive answers and suggestions. Many grateful thanks and positive wishes x.