Brother got engaged after, set date two months before ours

Also, didnt put my real dates in if anyone was wondering.

Yes she is being a little (err a lot) Bridezilla. (But please don't start the conversation with her by saying that!) Maybe give her a bit to calm down and then discuss with her again? I always am a big perponent of seeking a therapist. My FH and I have gone a few times when we've felt a little frustrated or disconnected and it really does help to have a third uninvolved party there to help get to the root of what is going on.

Wow is she normally this irrational? Seriously that is a way overreaction. Was that her knee jerk response in a moment of stress and now she’s calmed down?

I can kind of relate. My older sister got engaged a month after I did. We already had our date and venue set. Anyway I kinda “held my breath” until I knew their date thinking she would try to “beat me to it”. They initially set their date for 5 months after ours and I was relieved. But then they kept talking about changing it to perhaps a couple months sooner and I started to sweat again. But then they changed it to October of next year. And I’m married now. So anyway I understand your reaction of not being thrilled, but don’t understand hers that you can’t attend theirs or invite your family to yours.

She sounds like she's being way too dramatic about the whole thing. If she is always like this you should really consider couples counseling and if you really want to marry someone like her.

My situation was a little different, my FH coworker got engaged shortly after us. At a after work happy hour was
Happily talking about wedding planning and giving her tips and advise. One was how we settled on our wedding date (04/20/2019) and she mention that spring of 2019 was the time of year they were thinking of.* that was the only thing that they had agreed apon* Fast forward two weeks later another after work event, other coworkers informed us that that same coworker had finally pick a date... the exact same day 04/20/2019... I was so upset and hurt that she stole our day. Confronted her that same day, and she had the nerve to pretend she "didn't know that our date was 4/20" when i called her out on the BS statement her FH was visually shock and upset at her for clearly hijacking out wedding date. I haven't spoken to her since and don't know if they ever changed there date. Your FW she has a right to but upset but is overreacting. My fear was that she was going to upstage our day, and our day would be not remembered, maybe that how she is feeling. It also make it hard for out of town family to come to two wedding so close together so they are gonna have to choose between the two. Her stance on your family and disowning them. May stem from her wanting them to understand that it was messed up in what they did and stand up for you and her.
Hope this helps