not bear thinking about

Verb

(UK) To be too frightening or upsetting to even contemplate.

Japanese Meaning

考えることすらできないほど恐ろしい / あまりに驚くべきあまり、考慮するのを避けたくなるほどの恐怖を感じさせる

The scale of the disaster does not bear thinking about.

災害の規模は考えるだけでも耐えられないほど恐ろしい。

Sense（1）

(UK) To be too frightening or upsetting to even contemplate.

If the train had come just five seconds earlier... well, it just doesn't bear thinking about!