YOU SAID:

Are you sleeping with my sister

INTO JAPANESE

私の妹と一緒に寝てる

BACK INTO ENGLISH

I'm sleeping with my sister

INTO JAPANESE

私は私の妹と一緒に寝ています

BACK INTO ENGLISH

I slept with my sister.

INTO JAPANESE

私の妹と一緒に寝た

BACK INTO ENGLISH

I slept with my sister

INTO JAPANESE

私は私の妹と寝た

BACK INTO ENGLISH

I slept with my sister