Untitled for now

sorry i dont have a title for this yet but this was the opening for my english work this year because i have to study english language :D
====intro====
It only took seconds. Three of them, to be exact; each nanosecond I can remember as vividly as the moment it began. Each nanosecond in perfect detail... gory, horrid detail. I wish I could forget but I know I can't and that's something I'll always regret.
The insufferable screams that echoed in the halls, the sobs of my family as I watched them all burn; I told myself I couldn't do it.
But I could, and I did. As everything burned to ashes around me, a smile curved up my lips, I was terrified for my fate after I left the cabin but I knew... that I did this for a reason. This time the only way was the hard way... As I could felt my life fading and the walls around me crumbling, doubts seeped into my mind like toxin and as I threw the first matchstick to the oil-coated ground I heard Ellie singing from the dank cellar, her soft voice laced with persuasion. When I was young she had sung to me, as I was the youngest of four siblings, and since the age of 6 I had been dumbfounded without her by my side. Whenever i was sad she was always the voice inside my head, or the smiling face beside me; and now I was watching it burn.
What ill fate had besotted me, that day, I don't know. But as I limped back to my car, watching the whole place burn to ash, I had to smile; both sickened with myself and exasperated with the frenzy of bloodlust. As I drove back to the bridge in utter silence, I had time to think. My inner thoughts hounding me like wolves to the hunt, guilt quickly drove me to the virtual line of insanity where I remained, borderline-bipolar, for three weeks. After I got back to the city, nobody knew my deeds, everyone mourned the loss of my siblings and friends, and I couldn't tell them. Nothing within me could conjure up an excuse for why I did what I did that forlorn night in mid-August in that ramshackle cabin. 
Something else I remember is the bitterness that thing had, it had taken over my sister and every word was laced with an agonizing guilt-trip. "When you left us, Robin, with a sick mom, when she asked us where you were every day..." 
She was the last one to burn. I didn't know about the secret tunnels through the basement, but I burned her. Now I know that the thing wasn't my sister, nor was it even human. As I watched Ellie burn, her face remained expressionless and her movements remained still, even as the skin off her body was melting away. Oh, the way she smiled when she finally fell to the ground... I remember my heart racing when she flashed me the glint of hell itself, and I recall every single emotion that surfaced when I saw it. Nothing I have ever seen will replace the fear I had that moment, no normal being would smile that way when they were being burned... 
And now I don't know what to think, because I told her she was at peace... that night was all my fault... if only I'd left when she told me something was wrong. The first day we arrived, she told me the whole place was dead. If only I knew then, what I know now... I would have stopped this. My family would be alive. Chris, Sammie, Jaden would be alive. Everyone would still be here right now and I know I have only myself to blame.