I have a writing complication/I made a mistake

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So! In my last chapter of A World Without Me (chapter 2), I left some of the end off, as I thought I could incorporate it into the start of the next chapter, but I ended up going back to what was once a small paragraph and turning it into a huge 2,000 word section that doesn't fit at all with the start of the next chapter and it's really annoying me >.<
And I'm not sure what to do >.> I don't want to have it at the start of chapter 3 because, even though it's probably okay, I've wanted all the chapters to be self-contained and this would ruin that. It'd be like someone putting a cream onto a chocolate chip muffin! It's not right. I'd rather just have the muffin by itself, thank you very much. Stupid cream.

I was going to just add the story chunks to the end of chapter 2 but so many people have already read it that when chapter 3 comes up they'll have missed some important things. I was thinking of doing that and leaving a note at the start of chapter three about it, but then the readers would have to go back to chapter 2 and read some of what they've already read to get to the new thing.
But maybe that's fine and I'm worrying too much?
The other thing I thought of doing was having a chapter 2.5 and uploading it separately, as it is a fairly decent size. And then just leaving it there or in a couple of months incorporating it into chapter 2 and removing it? Or would just having a chapter 2.5 be fine? I've seen people do that before. I'm worried that people who've read the story might miss it or think it's not important, but I guess I can add a note to chapter 3 about reading it because it's important.
That seems like the best idea for now? Has anyone else been in a similar situation/seen a similar thing done?
Thankyou ^_^

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