My sister/MOH is throwing me a bridal shower. One of our mutual friends (who I didn't plan to invite to the wedding) found out via Facebook about the shower and sent her a tacky message like "guess I'm not good enough to be invited to the shower." So my sister caved and invited her, pretending it had been a mistake. However my sister wasn't aware that she was not on the wedding guestlist and I know it's rude to invite someone to a shower and not to the wedding. So now what do I do?