Equestria has become a dark and twisted place, pushing Derpy over the edge. When she goes too far it leads her to a series of events nopony would have seen coming. And she will smile again, whether it takes nine….or nine hundred lives.

If you could not figure it out by the title, though I don't blame, it's a ponified version of "The Cat Lady"
"The Cat Lady" belongs to the amazing people who made it.