*寿命を売られるところ=the moment where my lifespan was gonna be sold
 (reminder that tense doesn't have to agree in japanese unlike english(ex:yesterday he told me he
 was a teacher(he's still a teacher in the present))
*食べているところなんです feels like "I'm at the moment of eating (something)", and 食べているんです means "I'm eating".( 食べているところなんです answers "What are you doing (at this moment)?", while 食べているんです is for "What (kind of action) are you doing?")