YOU SAID:
my girlfriend cheated on me, she is a bad girl.
INTO JAPANESE
彼女は私をだまして、彼女は悪い女の子です。
BACK INTO ENGLISH
She tricked me and she is a bad girl.
INTO JAPANESE
彼女は私をだまし、彼女は悪い女の子です。
BACK INTO ENGLISH
She tricked me and she is a bad girl.
That didn't even make that much sense in English.