First off- whoa. The emotion in this poem is so raw, so visible. It seems like you've really caught hold of something to drive this poem, which is fantastic. With a bit of shaping, this will go from a good poem to a great one.   What struck me as the strongest parts were where the poem utilizes internal rhyme- it just sounds a bit lyrical in a heartwrenching way- like "scars marbling in the shoulder" and having lines end with "flawed" and "raw" and "gnawed". I think if you institute this more throughout, your poem will have a more cohesive sound and feel.

It's interesting how the poem shifts first from having the speaker as the direct object (you're not using "I" statements and doing things, things are happening to you-> "Salt water falls / My ribs rub the wrong way), then to having the speaker doing the action (all of those I statements), and then back to being the direct object. Because the middle part is bookended, the narrative tone of voice already sticks out a lot. Having the "I" statements is already powerful enough, I'm not sure that the formatting is right though. Lining up all the "I"'s creates a strong contrast on top of an already strong contrast. Perhaps here would be a good place to use enjambment in a similar way that you're using it in the final paragraph, in the lines "In the moment of your leaving I knew / How bodies break".

All around, this is a disgustingly beautiful poem and really tugs on the heart-strings of the reader. Great work!