We all lie

Prologue:
Kara's point of view:

It was the six of us, Emily, Miles, Alicia, Vinny, Seth and I. We had all been told a secret.
"If anyone ever hears about this secret, other than you guys, I will kill," we had all been warned. Our minds had been programmed and we could no longer remember who had given us that warning. We never talked about the secret, for in fear of the warning becoming reality.
But Nina was different, she was new to the group, the seventh member, and she was currently unaware of this secret. We all sat huddled in a group, around a lit candle, which lit up a tiny portion of the long, lonely field we sat in. Nina needed to be told this secret, she seemed trustworthy enough, surely she would keep the secret, secret.
"I feel a bit nauseous," I broke the silence between the group. Their tired, dreary eyes all stared up at me as I stood up and began to venture away from the group. Nina followed me and we retreated to a forest, nearby the rest of the group. We walked in silence, until I felt the urge to break it once again.
"Nina," I quietly said.
"Yes?" She stuttered, her body shivering from the icy, cold breeze. The trees moved slightly, humming with the wind, and the forest seemed almost peaceful.
"I need to tell you something," I began, "but you cannot tell another single soul. No one can know I ever told you this and you can't tell anyone what I'm about to say." Would I regret this moment, maybe I should've waited to tell Nina when I was more comfortable with her. But ever since she had joined the group, we'd become very close and her presence was humble, I knew I could trust her, but my heart was torn between my decision.
"What is it," her petite voice disturbed my thoughts. I looked over to her, studying her pale skin, and slim face, with long, thick black hair falling into ringlets down the side of her face. She was very beautiful and in the moonlight, her pale, blue eyes shone like the stars above.
I clenched my teeth together and began. "Emily, Miles, Alicia, Vinny, Seth and I, have all been told this secret. We can't remember who told us this, but whoever did, saved us from years of torture. This happened a couple of years ago. We killed a girl. We murdered her. We were so scared to tell anyone in fear of knowing what was to happen next to us. But than he came, and told the police that he was in fact the murder of this poor, innocent girl. We're sure that he has been locked up in jail somewhere, but we're always on watch that he will one day come back and find us all. We were warned to never tell anyone of this, otherwise we'd be killed! That's why you mustn't tell anyone of this! Not a single soul, never even speak of it again. I can trust you Nina, have I made the right decision?"
As soon as the words left my mouth, I regretted my decision. Nina stared at me, speechless. My heart was thumping madly, and my mind was spinning. Nina suddenly walked closer to me and embraced my body. A flush of warmth filled my body and I suddenly felt safe again, in her arms.
"You can trust me," she whispered into my ear. My whole body realised from the tension that had filled my body. Suddenly, she pushed my body away from hers and I feel to the ground, onto a pile of sticks and stones, which ripped through my jeans and teared at my thighs. Nina had stopped frozen and was looking into the distance behind me. In a flash, she disappeared and I was left screaming out her name. My words were caught in my throat, as my jeans were beginning to soak up with blood. Stones and rocks were deeply stuck in my thighs and I swear I could feel a sharp pain against my bones. A hand grabbed my mouth and dragged my body backwards along the ground, my legs furthermore collected rocks and stones, which ripped through my jeans and skin. My body was thrashed up against a tree and through my blurred vision I could see the outline of a body, already knowing who it was. It turned out that 'he' was not a boy, but a girl. The last thing I saw was the bright flash of light from the sharpest tip of a knife, which plunged through my skin, into my empty stomach.
"Secrets, should be kept secrets," was heard from my murders voice.