not bear thinking about

/nˌɒt bˈeə θˈɪŋkɪŋ ɐbˈaʊt/

/nˌɑːt bˈɛɹ θˈɪŋkɪŋ ɐbˈaʊt/

to not bear thinking about

to be so unpleasant, disturbing, or frightening that it is difficult to even consider or imagine