I have some advice for Demi coming from a kind place.
It's time to address this stuff, it's probably driving you mad every day thinking people are going to find it out. It can't be healthy to have the anxiety about all of this stuff.
Own it, say "yeah I did make those hate threads and I did do a number on that MUA but I've changed and I am sorry"
It will feel so much better owning up to this and moving on. Probably get a load of views and revenue from it too.
I think everyone would honestly have more respect for you if you were truly sorry about the MUA and the dobbing your poor little brother in for something he totally didn't do.
Just a suggestion because we know you're reading this
The problem with this and although on paper it seems like the right thing to do and she could gain some respect, things like this can also back fire.
Especially when you're on social media and it's your working platform. Eventually companies will realise "Well she isn't trustworthy" and so on and before you know it it could be a case of she'll end up losing her YouTube contract. Which is pretty much her only income. She could lose followers. Subscribers and so forth all because she was trying to get one up on other Youtubers. I still don't condone her behaviour towards the MUA and I personally think she should be on her knees apologising for that.
I have no doubt at all that this stresses her out and I'm sure she regrets it all the same but if you were working in a company and found out someone was being an absolute cnut towards others to save their own backs, you wouldn't wany anything to do with them, regardless if they have changed or not. I know personally I wouldn't. I'd have wrote them off. Especially if I knew a YouTuber was being horrible and there's been a couple out there I've stopped watching due to the lack of respect for them. That's essentially what could happen. So although I do agree with your statement about her owning up, she's not going to based on knowing the consequences also she could well and truly just be a horrible person. Seems like we've all made our decision on Tattle.
Demi might be in the mind set of, if I just ignore it and play stupid to it all, it might go away. Which doesn't sit well with everyone. People want her to fess up and I would love for her to just rip the plaster off and deal with the consequences, but when YouTube is your life line basically, you've no choice but to just deal with it as you go along and hope to jaysis that it'll get to a point where people have forgotten about it (which let's face it, once it's online, you're truly fucked)
Personally after reading this thread and previous ones, the Demi I liked before has now turned into the Demi I would have running in the background while I was cleaning rather than paying attention. Unfortunately she has brought this on herself but the bottom line is, she won't ever admit or apologise for anything.