YOU SAID:

I caught my mom kissing my ex boyfriend

INTO JAPANESE

私は私の母が私の元ボーイフレンドにキスをしました

BACK INTO ENGLISH

I kissed my ex boyfriend by my mother

INTO JAPANESE

母に元ボーイフレンドにキスをした

BACK INTO ENGLISH

I kissed my ex-boyfriend

INTO JAPANESE

元カレにキスした

BACK INTO ENGLISH

I kissed my ex-boyfriend