My heart is still racing. Wow. From the line "You don't usually look at yourself," I knew we were in for a rough ride that would resonate with me pretty heavily.
I was filled with dread, then revulsion, then dread again, and then outright fear by the very end. Your writing is so incredibly visceral and evocative. The use of second person was a really interesting choice, particularly with the mirror being so central to the story, and I think it helped immerse me even more. The flashback scenes were horrible and brutal, and in the present time, you did such an excellent job of writing what mindless compulsion feels like.
This is a deeply affecting story, and the sparse use of images really accentuated the writing. Well done!