Oh, please. One of my favorite "fluff" tv shows is Say Yes to the Dress on The Learning Channel. It takes place at Kleinfelt's in New York (apparently world-famous?). Anyway, just today, on a single show, out of four brides who purchased white dresses, at least two were 100% NOT virgins - and so, by the OP's frenemies' 'standards', not entitled to
wear those dresses.
One had married quickly a year or so earlier, just before her mother passed away so her mom could be there. Now she was having the whole big wedding thing, complete with, yes, gorgeous white gown. The other had been with her fiance for nine years; their six year old son was going to be, in his own words, "the ring barrier"

He was adorable - and yes, his mom was wearing, you guessed it, a white gown.
OP - pulling from a couple of the suggestions here (you both know who you are

), you could tell those twits that etiquette* states it's acceptable for ANY bride to wear a white wedding gown, provided she balances it with black or red lingerie from Frederick's of Hollywood... as you have already arranged
*I can change my name to Etiquette if it will make you feel more comfortable, i.e. you wouldn't be misleading them.