I'm looking for an outside perspective on this situation. I absolutely adore everyone in my fiances family with the exception of one sibling. I've only met them once, and it ended up being one of the worst experiences in our whole relationship. They claimed they were broke but wanted to come see us and join us in some activities, so my fiance paid for their travel and I paid for some of their tickets to activities we wanted to do, having never met this sibling before but just wanting to make a good impression. Well not only did they not say thank you for any of this, they criticized literally everything and made negative comments all day, then dropped $$$ at a gift shop despite being "broke." They were also extremely rude to me, made no effort to get to know me and instead every time I tried to walk next to my fiance or hold his hand they would literally physically push themselves between us and try to pull fiance off by himself to look at stuff. So I ended up mostly walking around by myself all day at the place I had bought everyone tickets to so we could enjoy it together. It sucked.
I talked to my fiance about this and he acknowledged my feelings. But also made a lot of excuses for sibling. Basically he explained that this is just the family dynamic with this sibling, that he acts this way because he's terminally single and lonely and unaware of social cues and norms because of their ADHD. I disagree, this sibling is 40 years old and I don't think this kind of behavior was accidental.
Since then, this is also the only family member that's made no further effort to get to know me. They're the only one who hasn't added me on social media or asked to exchange numbers. They're the only one who didn't congratulate us on our engagement. They didn't even "like" the relationship update on Facebook. All signs point to they don't support our relationship. They're the middle child and fiance is younger, I think there might be some resentment that he's getting married first.
Now comes the wedding planning. We just want a small wedding with only the very closest friends and family who have always been there for us and will be happy to celebrate our relationship with us.
Initially fiance wanted to invite this sibling because "they're family." But I have toxic relatives including siblings that I'm not inviting because we agreed that we're having a small wedding so we can specifically only include people who will be nice and are supportive/positive people in our lives. Originally when he brought it up, I expressed my concerns about having a repeat of this behavior on our wedding day, and we started making plans for who can babysit sibling to make sure they behave, and who we can have escort them out if they have a tantrum.
Eventually I was just like, why are we doing this? And instead asked my fiance if we can just not invite this person. He eventually agreed we can just not invite him.
But then I've been reading things online (I know I know) that make me wonder if I was wrong to even ask to exclude this person?