Wow Yack your boyfriend is between a rock and a hard place. His brother must be a real jerk to put your boyfriend in this position. I am very curious to find out how this plays out.

I agree with Doh2007, take the high road. Show the family you're the better person...this time. It is his wedding and he is entitled to invite whomever he wants. He sounds very immature and self-centered to omit inviting his brother's significant other of 8 years and leaving his brother to do the diry work.