YOU SAID:
I’m so confused by this
INTO JAPANESE
これによって私混乱しています
BACK INTO ENGLISH
By this I am confused
INTO JAPANESE
これで私は混乱しています
BACK INTO ENGLISH
I am confused by this
INTO JAPANESE
私はこのことで混乱しています
BACK INTO ENGLISH
I am confused by this
You've done this before, haven't you.