In the wings

I know my lines. 
I know the exact moment to touch that button on my dress. 
I know where to stand, the invisible 'x'. 
But my face is all wrong. 
But my timing is off. 
But my hands can't, won't stop shaking. 
So there's my cue, and I go. 
Wrong foot forward
This instead of that
The lump in my throat 
chokes
me
And I miss the invisible 'x'