I found out about my shower

My wonderful sister called me on saturday to ask me if my guest from Jersey are invited to my shower. I said of course why not? She said b/c they have yet to receive an invitation for my June 4th shower. Yes she said june 4th. I told her why did she tell me the date. She thought I knew already? UH no....I did not know... I had a feeling it would be in June but I didn't know the date. I am so upset . I told Fh about it and told him not to say anything to anyone. Why would she ruin this for me?

why do people do this?! Could she possibly be trying to throw you off?
I knew about mine and it was annoying but in the end I had an AMAZING time and so will you!