You're right about some of it being slightly overdone, but hey, if that's how you feel, then there's nothing wrong with repeating it.
I like the descriptive words (gashes, steel, metal, gore, ect) and the images they create.
I love knives and blood, so I can only give you compliments.
A sad truth. It was well conveyed but it still felt sort of distant. Almost as if it was being told from the perspective of someone who didn't know the full story, rather than the perspective of the actual subject who was facing the music.
I like the percussive rhythm emphasized by the short lines, but the topic just seems so trite and overdone not just the phrases you mentioned in your description. And that in and of itself really depresses me, because so many people are plagued by this serious psychological problem and it's become trivialized because it's become mainstream.
That said,
some of the lines don't make much sense and seem like your trying to force the rhyme.
It's like forcing yourself to bleed after you've cut, it's silly. If the cut is deep enough, blood will flow freely. If the poem is deep enough, the words will flow freely---don't feel obligated to make it rhyme.
If you do cut. I recommend getting help. I know from experience how difficult it is to quit. Not necessarily psychological help, sometimes it just exacerbates things. But there is no help like a good friend, or even a open minded stranger.
I don't mean to come off preachy or anything, but if you do an edit and want suggestions just let me know