不倶 ふぐ戴天 たいてん
fugutaiten

Noun

1. cannot allow (oneself) to live (with someone) under the canopy of heaven; cannot allow (the sworn enemy) to live in this world; irreconcilable (enemy)

Yojijukugo
不倶 ふぐ戴天 たいてん てき われるほど、どうしてそんなに きらわれたかなあ。
fugutaitenno tekito iwareruhodo dōshite sonnani kirawaretakanā.
He said I was his archenemy. How did we arrive at a situation like this?