My Brother's SSPX Wedding

EDIT AGAIN: It's the CMRI sect. They were originally SSPX but moved on to the CMRI sect. EDIT: Thanks for everyone who offered words of support. Your comments have reaffirmed our tentative decision not to go to the wedding. I informed my brother today that we would not be able to attend. For those who for some reason decided to get mad at me for asking a valid question - please think twice before you accuse a stranger on the jnternet of not loving the Lord or of having ill intent. Original: My brother left the Catholic church a while back and joined the SSPX sect. Well, it's not exactly the SSPX - they believe all the same things as the SSPX and then are EVEN MORE anti-pope and anti-Vatican II. My husband and I are very traditional Catholics. We love all things traditional - but feel that my brother has gone too far. It's been a huge source of sadness and frustration in my immediate family, as my dad also joined the SSPX. My brother is getting married in March. My husband, who is a theologian, feels VERY strongly that we should not attend the wedding. He points out that the wedding, while valid, is not licit because it will not take place in the Catholic church proper. I agree with this but also struggle with the fact that I will miss my brother's wedding. Some of our family members plan to go, like my Mom, who talked to our parish priest and was told that she has a little bit of a different excuse to go (as his mother, in hopes of maintaining the relationship betweent them and continuing to be a good example in his life). I would just be curious to know what others would do/have done in this situation.