Dear ella_1986:

I read your post: you read like an intelligent, sensible, kind and socially aware and skilled person. My advice: end all personal communication with  Sally. If all it takes to accomplish this is to delete Whatsapp- do so. If it takes telling Sally that you do not want any personal communication with her- then do that.

You should not be blackmailed into any personal relationship, and particularly not into a twisted/ low quality one. You are a quality person deserving of quality friendships, based  on the personal freedom: to be or not to be in a friendship.

anita