I've had nightmares and stress related dreams before, but nothing this vivid or personal. I will do my best to recount the dream in as much detail as possible. Thank you!

The dream starts with me running up a spiral staircase with no apparent railings and what appears to be inside a home, in the middle of a grand room. The home is well lit and decorated in modern furnishings, very bright and cheerful. In my right hand is a dull butchers knife and I'm in the midst of running up the staircase away from a dark-haired, female predator. She too has a butchers knife in-hand. In the dream, her intent is to stab me, maybe even kill me.

Fearful, I jump from the spiral staircase onto the main landing; the female predator follows in suit. I turn to face her in the open, she lunges forward and thrusts the butches knife with her right-hand. I dodge her advance, jut left and turn to run, intent on evading her and not harming her. As I do so, the scenery changes and now find myself in an unfamiliar bedroom. A well lit room with modern furnishings; a queen sided bed to my right and a vanity to my left, straight ahead is the bedroom wall to the outside with a small window. Realizing my predicament, I turn to face the woman. The woman is no longer the predator she was before, but instead my younger sister. She is crying, of current age and not carrying a butchers knife.

My surprise is accompanied with an adrenaline rush to my head, attempting to make sense of what has happened and where I am. In the midst of my clouded state Courtney, my sister, passes by me silently, turns and slides down the wall to face me. All sound has been removed and we begin to speak telepathically, "I'm hurting," she says as I squat down to face her. I remember the butchers knife in my right hand and reluctantly show it to her. By now, I'm crying too and say, "Do you want me to stab your stomach or cut your throat?" Tears stream down her face as she motions to her throat. I can't do it, I think, as she reaches for the knife in an attempt to do it herself. My heart raises, she closes her eyes and with a shaky fist, I bring the knife to her throat. Knowing I would have to press harder because the blade was dull and only wanting to do this once as quickly as possible to ease her suffering. The blade cuts and pulls across her throat, making minuscule tears along the way. I feel the length of the blade cut it's way through the folds of her flesh, pulling away as the tip reaches the opposite side of her throat. A momentary sense of calm comes over me as I inconceivably think, "The knife did not cut that deep and all will be well," like a paper cut that could be healed with a band-aid. She lifts her head slightly and the cut slides open and what should be blood, appears to be old motor oil flowing out down her neck onto her blouse. At first, I'm disgusted and don't want the oil near me, this thought is quickly erased, as the realization of what I've done comes over me. Frantically, I lean forward, shooting out with both arms in a attempt to scoop her up into my chest and stop the bleeding. Her body becomes weightless in my arms, her head drops down onto my left shoulder next to my cheek. I sit there holding her tightly as her life-force gives way and still no sound.
...
I wake around 11:30am and instantly feel sick to my stomach. Pulling back the covers and rushing to my bathroom in a staggered dream like state. Standing in my bathroom hunched over and nothing lurches out. Glimpses of my dream start coming back to me as I remember slitting Courtney's throat and her asking me to relieve her pain. I wake my husband and recount the dream back to him, sobbing into his awakened arms as he holds me.

It was hard to sleep after that emotional dream last night as every time I recalled cutting my sister's throat it haunted me and the tears would start rolling forward from behind my eyes.
I have not spoken to my sister in over 7 years. I'm currently writing my memoir and had a glass of wine before bed last night. I mention all this, to just clarify the situation and assist you with a better interpretation.

Thank you in-advance. Sorry for the novel!