This isn't necessarily "your" problem....it IS your husband - while you are "family" the fact is that that is HIS aunt...HE needs to step up and tell her to knock it off - if he can't do that - then he doesn't respect you enough to keep his family in "check"....
I would also stop going to family functions....they may not like it - but if all you get is ridicule from them - then WHY put yourself in that situation? Your husband MUST step up to the plate and tell his family HE IS HAPPILY MARRIED AND TO BACK OFF!!!!
It also sounds like his family is testing your "mettle" or worth - crappy thing to do - but I would tell them all to pound sand. I'm bold that way. I had problems with my MIL - I told her FLAT OUT - HER SON IS HAPPY if she can't see that or doesn't like that - well,she can talk to HER SON and tell HIM to his face how she feels.....that changed our relationship forever. She knew I was in it for the long haul, etc....
GOOD LUCK!!