I've been wanting to tell you about my sister. When I was five, X and I would play with our Barbie and Ken dolls on the big wooden dining room table. We used books as room dividers, stood on their sides, piecing the table up into different rooms and apartments for all our Barbies and Kens (we had many). Our dolls had sex together, mashing their pelvises together at a curious diagonal, while standing up. We weren't aware of anything but heterosexuality, but we called the sex "muhfky-fuhfky" (a variant of "fuck"?) One day, my sister X, who was four years older than me, started tearing the heads and arms and legs off my female dolls. She didn't take any off her own. I was very frightened. When I complained, she just showed me where she had heaped my dolls' dismembered limbs and heads. Seeing the torn-off parts unbalanced me, too, as though someone had done that to people. But I couldn't get their arms and legs and heads back on again, and I had no more pleasure playing with my dolls again.
I don't know if this was the same point at which X began hitting me and biting me. Our four-year age difference made her far stronger, and I quickly became fundamentally afraid of her. Her potential to harm me seemed uncanny, as though she were a werewolf or a ghost. She was always telling me she would "get me," which meant to me something like magically kill me or disable me via some gesture I could not resist.
One day, after X had done something scary to me that I can no longer remember, she came back into my room after I had finished crying. I told her I was angry. She said: "Oh no, I didn't do that to you, that was the bad X. I'm the good X!" I was horrified that she was trying to make me think that she was two different people (did she really think I was that dumb, merely because I was little?) Years later, I wondered if she did actually see herself as two people.
In our 20s and 30s, X and I actually became close for a while, when her sweet, warm, and mushy half would come out and nurture me. We would talk on the phone every night, tell each other about our day, she would even speak in a weird sort of baby talk to me. I didn't like the baby talk, but I liked having that warm connection with her. We would hang out on weekends. All until her menacing side would come out again and she would get in my face, call me "piece of shit" and "stupid," and try to force me to do things (give my stereo to her friend, spend more time with my mom, "move!" out of the precise point in space I occupied so that she could get in there instead).
Thankfully, I finally realized I was fully grown, and she had no power to force me to do anything if I didn't let her get near me. I stopped being in contact with her.
Sometime in my childhood, when I had only recently become a writer — 11, 12? — she tore up my writing. This was before the computer era, and it was the only copy of something I had written by hand. She hadn't read it, she just tore the piece up because it was important to me. No one has ever torn up my writing since then, but that elemental fear — that some writing I made would be torn to bits, as though I myself had been torn to pieces in a single moment like a piece of paper — has stayed with me. The sensation of what it must feel like for the paper to tear. Being fully effaced. The burning hurt of being torn across the web of my body in one easy motion, loud, so that no one could ever know me again. For it to be as though I’d never existed.
Whoa! I relate to this story. My sister is four years older than me and loved torturing me. Yours sounds a bit more extreme, but I feel your pain!