Stellar my friend!
Just I'd like to give my opinion

A gun sitis loaded
Held to your head
I can already see it
The room painted red
The word 'sitis' differs from that in the last stanza 'sits'! Which one is right? 'Held' if replaced with 'directed' would read better.

But with who's blood?
The word 'who's' I think you mean 'whose'

Ready and loaded
You want to fire
I can see it in your eyes
The burning desire
This stanza is very good

How could you do this?
Want to leave?
While I'm left here..
Alone, to grieve.
I think 'could' should be in the present tense 'can'

You hold the gun
Trigger ready to be pulled
I jump in front
Suddenly laying cold

A gun sits loaded
Held to your head (again 'Held' should be replaced)
Now you can see it
The room painted red

This aside, I enjoyed the reading.