I'm trying to figure out how to read this. I did it with separate voices in my head, reading the two apart, line by line, etc. All ways work fine. And that's great, the multi-purposeness of a poem. Giving the reader real freedom. Not only in the way they interpret it, but also the style in which it's being read.
I don't know the official nickname for this type of poetry but I like to refer to it as parallel poetry, in the way the two columns run parallel and feature two distinct features about, in your case, a mental battle on what you've really lost upon losing your companion, or brother, or significant other (the argument can be made referring to all three). I feel that you speak of losing someone to depression, hence the light vanishing from their eyes and the dead, non-moving limbs. The actual happening could be subjective, but I lean more towards the person whom bares the misery to be losing more: there is no greater woe than to lose oneself. You've expressed yourself well, as always, kristin. Lovely piece.