Obviously, there is a family issue as well. There is no way that I would spend four years going to family events where one of my siblings was shunned, and shunned for simply making a stupid mistake - one that he fixed for her. And something that he probably did out of love, no matter how people perceived it. No way, a strong conversation/change in dynamic would ensue.
I can also see that it was a painful time Shanti.
Just deal with her differently. If she starts shouting when you're trying to have a rational conversation, just tell her that you can't and you're getting off the phone. Also when talking to someone who is enraged do not change your words/sentences at all, not one iota. Just repeat the same words - short, firm and simple over and over. They are often looking for something else to grab onto.
If I cut a family member because they act inappropriately, well family would suddenly be quite a bit smaller.
Not happening. And heck, maybe my siblings think I've been at fault at times. Just somehow teach her what is not okay with you.
I fully understand the love that you have for your family, wanting to be together Shanti. Wanting that connection for your children and hers. It's important.
I think some changes on how you deal with her will make a difference going forward.
And don't underestimate the feelings that can come up with your father, and with your siblings around it. Just because you didn't have a relationship with him lately does not mean some feelings are not intruding on this time.
Also, don't think you completely know your own upbringing, as a family. Siblings can have an extremely different outlook on their past/everyone's past. And that doesn't mean one is valid and the other's outlook is not. Just speaking in general Shanti, not at you.
I get your decision of wanting your own space on the trip. I think it's valid and smart. But I also hear some posters that are openly wondering if she saw this as time all together, or saw it in a way that you're simply not seeing. Can you not compromise for one night? And book your own room at the same place.
And since you write like you are close to your sister, have you asked her what she is so angry about?