Hi Everyone! 
So I'm looking for some advice for whether or not I should invite my cousin's spouse to our wedding.
Some background: My mom is one of 5 kids, so I have 4 cousins (my parents had the most children, 3). The spouse in question is the spouse of the eldest cousin, who I am not the closest with because of our age difference. Her husband got along with our whole extended family when he first married my cousin 14 years ago. Over time however, he has definitely caused rifts and arguments within in the whole family, targeting my immediate family especially with gossip and petty social media drama, resulting in him blocking most of the extended family when we wouldn't play into it.
In the midst of the drama but before his social media meltdown, my brother invited him to his wedding. While there he didn't really talk to anyone and sat sulking at his table all night on his phone. He has been invited to other family events after he blocked everyone, like to my nephew's birthday party, but he did not come.
The relatives I am for sure inviting don't get along with him either. However, I know the etiquette states that if i am inviting any cousin and their SO, I should invite them all. In my case I have two married cousins and two in long term relationships, so if I didn't invite this spouse, one cousin would be the only one without a plus one. I don't want to causes any hurt feelings, but I should also point out that he hasn't met my fiance, even though we've been together for around 6 years.
Some family (like my brother) say to invite him and be the bigger person, and some say that it is our day so we should do what we want and follow our own rules. What do you think I should do?
