You know, if I were in that situation, I wouldn't know what to do either! The friends at the party are so stuck up they'd be rude to your best friend of many years? Whoa... well, how about this?
Take your friend out and get your hair and nails done and shop.... LOL, let your husband tell his snobby pals that you're off 'at an exclusive salon' having a 'treatment' or something. (pick some town out of the way so none of them knows it!) They may wonder why you aren't at the party at first but they'll probably all nod in 'understanding' of a woman of 'upper social circles' who needs her pampering in the fancy salons! LOL