Practice coming out wrong

The recital is coming, i know perfect practice makes perfect performance. Today the music is not perfect, my playing to my ears is torment. My mind is spinning from the unique chords and harmonies written The notes are not blending into each other, my hands not working as one I lay back on the bench and listen. The ticking of the clock is like a metronome; reminding me I can't perfectly play the song. Every key, black or white, clash with the others it's all coming out wrong.