Need some guidance on bad history haunting my relationship

I’ll be as brief as possible. And thank you in advice for your time and thoughts. My wife and I were invited to her brother’s dinner party for his birthday. The problem is, one of her brother’s friends will be attending who when he was 21 made out with and fondled with my willing wife to be. The problem is, she was much younger - 14 at the time. They were making out on a bed during one of her brother’s parties and luckily her brother come in and broke it up and kick ed him out. That was 15 years ago. They have since reconciled obviously. But I know this and i’m supposed to have dinner with this guy and his family knowing what he did to a 14 year old girl many years back. All I want to do is call his out for it in front of his wife and family and probably put a fist between his teeth. My wife knows this about me and said I should just stay home and she will go. She feels uncomfortable as well but doesn’t want to miss her brother’s birthday. I’m pretty upset she’s not more upset about this. She was willing at 14 but she’s a grown 30 year old now and should know how bad that was for him to do. Sure it’s been 15 years since but is that enough time to let it go? Should I be mad at her for not seeing that? Should I even be mad at him? Thank you for listening and any advice you have.