because of mimi he met cheol who he said "reminded" him of mimi, so if mimi didn't die then he wouldn't have met cheol but knowing how crazy minyoung is, i doubt it
He was addressing his parents then after thanking his parents he asked mimi if he liked his present which was sending off the person who killed mimi to hell
i thought the ones who died in his place were his parents why he is thanking to mimi? didn’t that dog died from an accident