Used 

just like a tool in the shed

A tool of which you could surely live without

but you use all the same

And I am your favorite of the tools

probably because most of the other tools would reject you

I don't want to be used by you

but all the same let myself go

I have no control

I am numb compared to the pleasure you give me

And you know of this, user

You take advantage

You manipulate

You 

use