First off, I was unfortunately spoiled by leaks, but my heart was STILL pounding during the entire thing. I cried when Lars was supposedly dead despite knowing he was alive. That's powerful writing.

So I have a theory--probably not unique in any way, but I want to share while I still have these thoughts fresh in my head. People are suspecting white diamond as the true culprit and yellow having inside information. We need to consider these things along with Pearl's clearly intense reactions upon mentioning of Pink's shattering. Everyone also says that it was clearly a sword which shattered Pink, despite Bismuth saying it wouldn't shatter a gem--hence the creation of the breaking point. What if White Diamond was the one who came up with the cluster and wanted to input it sooner. However, Pink Diamond, while not "good" by common definition, still wanted to reason with the rebels and talk them down without more violence--especially because the leader of her own creation. So, what if Pink and Rose organized a meeting to discuss terms of the rebellion. Meanwhile, White and Yellow wanted a way to end the war. White suggested putting the cluster in immediately, but Yellow wanted Pink to escape first. They argued and eventually White decided to take things into her own hands. So White somehow intercepts information about this meeting and perhaps contacts her old pearl--our pearl--about wanting to take part in this to end the war once and for all. So Pink orders everyone else to leave so the meeting can happen in private. However, Rose is unaware of White coming because Pearl didn't tell her, perhaps wanting to impress her how she negotiated the situation on her own. So Rose and Pink argue, until finally they start to fight. Pearl and Rose run outside and while being chased, Rose stabs Pink with her sword. However, White Diamond uses some sort of power and shatters Pink because to her, the only way to end the rebellion and get her sisters on her side was for the one thing stopping the earths destruction to die--and that was Pink Diamond herself. So when gems (like Eyeball) come to Pink's rescue, White declares she was trying to fight against the rebels who ambushed Pink Diamond. Because the attack of Rose and White were so close, Rose and Pearl assume somehow that it was Rose who shattered her and ran from the scene. White pretends to be innocent and knows that using Rose as a scapegoat who shattered her youngest sister will be the last thing to push Yellow and Blue to use the corruption song and the cluster to obliterate the earth. Perhaps Yellow and White had a fight about Pink before this all went down. Maybe White thought she was weak and held them back--so that is why Yellow gets defensive when the diamonds are accused of shattering her.

Whew. Sorry, this all was a lot. It doesn't really make sense, but I wanted to get it out haha. I would like to hear anyone's thoughts!

TL;DR: White shattered Pink because it was the only way to get her sisters to destroy the earth and rebellion--Rose happened to try to poof her and took the fall, believing she killed Pink herself