Guest are not welcome

I have not sent out my invitation for my october wedding. Verbally we already told our friends when is our wedding. Last night, my boy friend told me that, 1 of his friend already told others that he will bring his girlfriend to attend out wedding. I feel very pissed off cos i really not intend to invite her due to some conflicts.... but my boy friend said, what to do? since he want to bring??? I very angry, its MY WEDDING!!!!! sigh
What can i do now ?