Best friend faking she is very innocent and pure

Hello ! I’m new ( while I created this account not long ago but i didn’t create it 2 week ago, I’m just not very active on it) so I still don’t really know how to use mangago. I don’t know if this topic is allowed either ( My native language isn’t English so I’m kinda having trouble here (;°^°) ). I am mostly asking this question to have some advice or opinions.

So um My best friend has been faking her innocent and pure personality for quite some time... Like she straight up says :” I don’t know” or “ I don’t understand” when we talk about more adult stuff. Since her and I love the same genre of books sometimes when she picks a book that isn’t made for kids and that I read it before her ( well more like if I’m going to start to read it on mangago and there’s people that save some images in their gallery I will sometimes see that there’s some things...u know?), So I will tell her ( but this was before I knew that she wasn’t totally like she seems to be) “Yeah be careful there’s some....ummmmmmm not for children things in there” ( well I don’t really say it like that...I don’t really know how to translate it so...) She will say “What Not for children things? What do you mean by that ? I don’t understand” in her fake high voice ( like baby voice, but I guess she doesn’t seem to notice it since when I introduced her to my cousin and that she complimented on her voice, she began to speak with a voice that is really different from what I knew..or if we talk about the thing I just said) I would respond to her : “Ummm well _+ things ?? You see...?” And then she would respond me : “ _+ things ? What do you mean by that ? I don’t understand what you’re talking about...”

Like girl I just made it clear for you ! I don’t know how to explain more then this ?? But my other friend just explain to her in an other way and she said : oh ! I think I understand now....” Girl we studied about it in school ! How do you still not understand??

But let’s pass, I have other things to say . Like how I know it is fake.

Well you see I have her YouTube account. You might ask me :”why do you have her account ?”
Well I was the one who created it. So it stayed on my multiple YouTube accounts.
I don’t go on her account a lot , like I went on it only 2 times.
The first time was an accident, I thought I was on my account but when I looked at the search history I knew right away that it wasn’t my account.( the browser history was filled with French, and I don’t usually watch French videos)
The first time when I went on it ( and it is also the time when I found out about it )
There was written and I quote “anime yaoi +_” I was shocked . It was the second search thing like.

The second time was today since I needed to see if this was the same thing than before. And try to guess what I saw...
Well here is the thing : The November, 22nd 2020 at 03:33 “H****i .
Like Wahhh ?

Well I want to talk to her about it. I’m not a saint or very pure and i know it... But you see I don’t want to hurt her since we’ve been friends since 1st grade...
Usually when I have a friend that tells me something but I know that it isn’t real, I say it right away. Like I had a friend that has the same interest than me ( drawing) she was very kind, but she keeps lying like she told us, her step father is abusing her, ( that might be real but her step father doesn’t seem to be that kind of person? ), she fell down into the subway railing when she was on a school trip ( in 2nd grade) and since she knew what to do when you are in this kind of situation, she put herself between the two trains, Her mom feed her cloth soap ( I don’t know this is called), she doesn’t feel pain ( but last time when one of my friend ask her if ,when the doctor put her braises on it hurt, she respond yes), she doesn’t feel cold ( even if we see her shaking). And the worst thing she did to me was she stole one of my character. ( my main oc )
As someone that is extremely possessive, I did not appreciate what she did.
We could totally see that her character was not supposed to be like this , like the thing at the beginning was supposed to be a guide and since there was something that is one trait that my character has she probably told herself, this is pretty cool I’m gonna keep it. At first when I saw this, I just thought this was funny, and then she told me her hair color ( which is the same color as mine) I thought okay?? It is a bit weird, and when she told me her character backstory ( i told my character backstory like 2 days before she did, in the subway) I thought Whoah ! Seriously? Why does her character resemble so much mine ??
She also used one of my best friend oc’s special traits and two of my other friends nickname for her characters . I guess she thought that we were “cool” ? So she tried to fit in us ?? Like I can understand but lying doesn’t seem to be the best way to integrate, so you’re more cool and quirky?? Well know we aren’t really friends but more like acquaintances. But she really left me with big trust issues...

But let’s pass this isn’t really the subject.

Do anyone knows what I should do ? Or like have some advice to give me ? It will be very appreciated!
(And I’m very sorry if it wasn’t very understandable.. And also sorry about the big text..)

( I don’t really know if this contains po********** information though? I guess ? Well this wasn’t really the subject, I just wanted to know what I should do since I’m not very good with word, but I won’t be upset if this is deleted.)

I hope you will have a very good day/ afternoon/ night.