I'm not sure that this poem is clearly about anything in particular. It does start off referring to the absence of something--which might or might not be a person--and that absence/loss freezes things as they were, disrupts things, brings everything to a halt. But I do not think this necessarily refers to the death of someone, or one particular person, since it says, "When you go away..." suggesting something that comes and goes, not something that has departed for good. Maybe she is referring to recurrent loses of people in our lives, and what we experience each time we have such a loss. We feel left behind, useless, impotent, like those shoes in the closet.
A pistol, which usually starts a race, suddenly stops all motion, so the author is using that image to alter our perception of the sequence of things. What kind of race is she talking about that we are watching? A nuclear arms race? Humans racing against time? Does the death of someone cause us to face our own mortality? She then seems to be referring to the anticipation of what might follow next "(betting the farm...")
and seems to be describing a past struggle or conflict which leads people to shed their past (to shed their "skin" like a snake?) and move on. This could refer to something, like the end of a marriage, the end of a war, death, or even the process of aging. We pass along, or leave behind, memories of ourselves, we bequeath things to others who are survivors, we talk about those who are gone, and we also forget them.
All of the above is simply a guess on my part. I don't think the poem is meant to be very clear. I think she wants the reader to use their imagination.
I found another view of this poem. You can read it here.