When invited to a wedding, are guests required to dress according

My father-in-law is getting married.  My husband is best man, my son is doing something during the ceremony like rolling out the aisle runner with one of the bride's grandson, and my daughter is a junior bridesmaid with bride's three granddaughters.  My son and husband are wearing tuxes rented by the groom and my daughter's dress was purchased by the bride along the other bridesmaid dresses.  I have no "job" in the wedding at all except for getting my family ready, so I bought myself a new dress for the occasion.  My father-in-law had asked what my dress looked like a few weeks ago and I told him.  Now the wedding is a week away and he has informed me that the bride doesn't like the color of my dress and because I may be in some of the "family" pictures taken by the photographer at the wedding, she wants me to get a dress in her chosen color.

Let me just say, I do not like this woman and she does not like me.  She doesn't like my husband either and I really don't think she likes my kids, but pretends to because my father-in-law adores my kids and they adore him.  She has already called to tell me that while she, her daughters, and her granddaughters are all going to salon on the wedding day to get hair and nails done, she expects me to handle all that with my daughter, to her specifications of course, because she is just getting so stressed out.  So the dress thing is just the final straw for me.  I have half a mind to return it and get another in dress in the most obnoxious color I can find!