AITA FOR KILLING MY SISTER AND DISGUISING HER MURDER AS A SUICIDE?

I (M14) am a violin player, I found my love for it through practicing alongside my sister (F18) for a duet we were supposed to perform 4 years ago, unfortunately, due to some circumstances, that duet has never been performed.
Four years ago, one day before the duet performance, me and my sister were practicing as usual after hanging out with our neighborhood friends. I got fed up, we kept practicing and practicing but I could not see myself getting better, it was horrible. I burst out of the room where my sister's piano is placed and was headed towards the stairs, the violin in my hands reminded me of my unimproving skills, so I destroyed it, I broke it.
Going up the stairs, my sister catches up to me and yells at the sight of a broken gift, all I could hear was screeching, i didn't even know what to do. In a fit of rage I pushed her down the stairs, I couldnt stand her voice anymore but she was gone, dead. I hurried down the stairs in a panic, I couldn't believe it, she was gone.
I wished to hold myself accountable but I was far too afraid, my friend (M14) was visiting us and was horrified at the sight of a motionless body down the stairs, he suggested we hang it to a tree in our backyard, I followed his suggestion in a daze and hung it. He said i'll be okay, he said it was something behind me. It was me.
AITA?