Thanks for the links, Cerne. The information there did help, although sometimes I was a bit confused about the subject since the website is devoted to workplace bullying. I got the overall picture, however, of a person who behaves much the same way as my mother has, but within a different setting.
The difficulty for me now is that I cannot figure out if I am dealing with a narcissist or a sociopath. My husband is quite sure she is a sociopath. Either way, it is a bad situation, and my mind and heart is rebelling against the notion that my own mother may not love me, may not ever really have loved me, because she is incapable of love.
She herself has frequently lamented that she doesn’t feel loved, and she is desperate to know what love feels like (making herself out to be quite the victim while she continues to treat me in an unloving fashion). She ignores or belittles my attempts to show her love, unless she is manipulating me into a very difficult situation where I must make a grand display of affection that is practically impossible to accomplish (long story, but the story of my entire life). She tells me to my face that my treatment of her and consideration for her is inadequate, but she tells me this as if she is not speaking to the person she is speaking about, but instead to a trusted confidante. As in, she “confides” in me that no one loves her and considers her feelings, including her very own children, who didn’t do anything grand for her birthday, and how much it hurts that her own children do not do more to show they care. Saying this to me. Her eldest daughter. About whom she is speaking horribly. Like I am not there or like I am someone else. Like I should become indignant about such ill treatment (which is always untrue).

Maybe I should start a different thread about this, since obviously, my sister did NOT really attempt suicide and it was all a huge joke and an opportunity to manipulate everyone into a “how much do you love me?” dash. Which tactic she learned at the knee of our mother, of course.