Annoying mother in law 😑

Technically she’s not my mother-in-law because I’m not married to her son yet but I call her that anyway. Me and my boyfriend were invited to his uncles and aunts vow renewal this last weekend and I was ‘casual ‘ so I was just gonna wear a sun dress but my boyfriend told me no ones gonna dress up and to wear jeans and a nice top. So I ask his mother if being her sisters ‘wedding’ and she told me to wear jeans too and I did. I was the ONLY ONE WEARING JEANS every other woman was wearing a dress and this was my first time meeting most of them. The looks they gave me would have turned medusa to stone. And my mother in law WAS WEARING A DRESS after she told me not to!! I don’t know if she meant to make me embarrassed myself or what but I honestly feel betrayed not to be over dramatic. No one would talk to me, if I was standing next to my boyfriend they would talk about me but not to me