wow that is a hard one. You want to respect both, but you have to live with your soon to be husband the rest of your life. You would hope that he would be the bigger man and get over it, but you have to think whether or not she would still be one of the bridesmaids. Sit down with him and let him know how you feel. However it might just be better to get someone else so that there is no fighting at the wedding. I hope I helpped a little bit.