YOU SAID:
i never knew it was you!
INTO JAPANESE
私はそれがあなただったことを知りませんでした!
BACK INTO ENGLISH
I did not know that it was you!
INTO JAPANESE
私はそれがあなたであることを知りませんでした!
BACK INTO ENGLISH
I did not know that it was you!
That didn't even make that much sense in English.