Burning alive

[Donald Q.]

Revised 02/18 5pm

My heart pounds and my breathe struggles.    Breath, not breathe. 
Each second seems like an hour as I stand there, helpless and ashamed. 'Each second seems like an hour' is a boring way to say time is standing still, you can do better I think. 
Still I watch your burning silhouette through the sheer blinds that shake as you writhe and scream. The image of 'sheer blinds' gives a sense of perversion, which is interesting.   
There's nothing I can do. 
No one to call. Doesn't seem very genuine. 
The fire has consumed you now.  All I can do is watch in horror until you convulse and collapse in a lifeless heap. 
Now it is silent, except for the pounding in my chest against my stifled breath. You already mentioned the pounding and breathing. Maybe get rid of their existence in the first line...
The patio light shines on me like a spotlight on a circus clown. Interesting image, again a bit peeping tom.
I creep quietly away, cold and alone,
because your fire no longer burns for me.  Okay, so I think this ending makes the implicit now explicit; that this is some jilted lover watching their ex. I think you've used an interesting metaphor which is actually pretty great, but there's some bits which are a bit too far earlier in the poem ('lifeless heap' seems like a bit too far, perhaps) 

I think if you are disciplined with your word choices this could be a wonderfully sordid little poem, look forward to reading a redraft.