隠し通す

かくしとおす【隠し通す】

continue to hide [conceal]; keep sth secret (for ever); never reveal 《a secret, the truth》.

●その秘事を隠し通して祖母は墓に入った. My grandmother took the secret with her to the grave.

・私たちは最後まで妹ががんであることを本人に隠し通した. We never told our sister that it was cancer. | To the last, we kept the fact that it was cancer from our sister.

・こんなこといつまでも隠し通せるわけがない. We just can't keep this kind of thing secret [hidden] for ever. | It simply won't be possible to go on keeping things like this secret.