YOU SAID:
ずっと前から知ってた
INTO JAPANESE
ずっと前から知ってた
BACK INTO ENGLISH
I've known you for a long time.
INTO JAPANESE
私は彼女とは長い付き合いだ。
BACK INTO ENGLISH
I have known her for a long time.
INTO JAPANESE
私は彼女とは長い付き合いだ。
BACK INTO ENGLISH
I have known her for a long time.
That didn't even make that much sense in English.