beside oneself

Prepositional phrase

idiomatic

(idiomatic) Overcome; consumed by an emotion.

Japanese Meaning

激しい感情に支配され、我を忘れる状態 / 感情に完全に消費され、平常心を失う状態

To be beside oneself with relief, he collapsed into a chair after hearing the news.

その知らせを聞いて安堵のあまり、彼は椅子に崩れ落ちた。

Sense（1）

(idiomatic) Overcome; consumed by an emotion.

His widow was beside herself with grief.