Call it blackstar, call it painstar
The same thing happens when you touch it
The painstar, is of couse a reference to Wurtz's Lamezone 001, in which the painstar is described as a star that you could touch to feel extreme pain for just a short moment. In this case, he relates the mirror breaking to the painstar, saying growing up and growing out of a relationship is an intense, meaningful pain for a short moment. There is more to this but I find it hard to explain.