dang, both of them were stabbed in the heart... And both were related to the Uchiha... Hmm and both the 2nd Hokage and Kakashi have the same white hair with the habit of stabbing people through the chest...
I mentally figured out everyone else, but who is broken heart... hmm... Kakuzu is still living, Shisui was mentioned the previous line... Maybe it is Izuna as he was stabbed in the heart by 2nd Hokage? It's common for the little wife to be joked about in chat group fanfics, plus two Uchihas being listed one after another in the list feels possible...