I agree with the girls on here, you should wear the dress you've fallen in love with. He will completely change his mind about yellow dresses once he sees you in it (I've seen the pic, it's brill!) and he'll love you in it because it makes you feel amazing.
If you change it for him, then you'll spend the rest of your time until the wedding trying to guess what HE thinks he wants, which you'll never match, unless you get him to choose the dress himself (bad idea, if he's like most men I know).
He has fallen in love with YOU remember, with all your 'yellow dress quirks' (my H2B has resigned himself to a bizarre wedding) and he will love that you feel great in that dress.
And yeah, find the blabbermouth and give her what for 