It is hard for me to be certain, but from all that I have read in the last couple of months, and all that I have experienced emanating from this "person" (I'm not sure if that word is the correct one for her), I have become pretty well convinced that my coworker of 10 years, who became my sister-in-law (by marriage to her only brother, who she introduced me to and who is NOTHING like her, fortunately) almost 2 years ago, is a destructive N. I'd had problems with her in the past at work, but it seems that since I married her brother, she has devalued me completely, and I find it best to try to avoid her as much as possible, in the very small office we work in and in our social lives. How can I know, and what can I do? I had hoped to somehow "make up with her" for the things that she *thinks* I've done to her at work and outside (if only she had a heart, she might be able to see that I have never, ever purposely done anything to hurt her or cause her problems; she on the other hand has been extremely toxic, mainly through negative gossip about me and through her general treatment of me), but I have come to the conclusion that this is impossible with a person such as her, and now I just basically treat her as she does me, like I "don't care" about her, and I try to avoid her as much as possible. Any advice??