Are you afraid of someone you call a friend?

Someone you became friends with who, over the years, has changed to the point that you are afraid of him or her. You are scared to be around them but afraid of what they might do to you if you outright ended the relationship....so you stay in touch as minimally as you feel you can get away with and try not to actually meet them anywhere in person. I have two people in my life like that; they give me nightmares and I am convinced they are crazy enough to kill me but I stay in touch because I am afraid not to. We once had a real, healthy friendship in our youth but that was a long, long time ago. Now...I feel it would destabilize them if I outright dumped them from my life and ended all communication. So I send birthday and holiday cards and an email now and then hoping I will never see them again.