Oh Cathy, what a shame for you. I think you are being very patient and it must be hugely difficult for you with your husband on one side and your daughter and the rest on the other and you stuck in the middle. My Sister in Law married a man 16 yrs her senior when she was only 18 years old. Her parents (my inlaws) were very opposed to the relationship. She has recently broken up after 23 yrs of marriage and three children. She once told me that she would have left him years earlier but she felt so embarrassed about the hurt she caused her parents that she felt she had to stay and make the distance. sHe is a proud person and I suppose she did not want to hear her parents say I told you so. I suppose I am saying that all the above wise words are correct. You need to state your case succinctly and once, but always be there to support and love your daughter no matter what. If we parents desert our kids who else will they turn to? I think you sound sensible and kind.
Oh and the other thing I was once told (too late for me) was to start your marriage out the way you wanted it to be. People will not change, never ever!! Please keep us posted and the best of luck and love.