Aw the sweetness! ^_^
Nath - You could always do the classic TV soap wedding thing and stand up and say your thing when the vicar says *does anyone have a probelm with these two marrying?* Not the exact words I know.. but you get my point.
Have you told your parents about what she has said? Asking your bf to back you up might help your argument too, if he heard what she said too.
I'd probably slap the cow... although I don't think my hypthetical brother would be too happy. Gah, this is such a difficult situation!!!!