How do I end or fixed my friendship with someone I don't get along?

Ok so Im in highschool right now and I have this friend named emma (fake name ofc) and when I first came to this school emma was the one who talked to me first and invited me to her friendgroup and it was all nice but then she had a fight with the friendgroup whice escaliated to the classroom and they all stopped talking to her. (from what I understood bc NO ONE still told me the whole story is that emma went and gossiped about some people whice the girl she gossiped with then told this to other people and it escalated from there this is something that needs its own post tbh) so ever since then she has been basically by my side the whole time, I didn't mind it first actually and she really did fixed herself a lot ever since that happened. She is basically depended on me like how a baby always follows their mom. She never leaves my side she ALWAYS wants to talk, whenever I don't go to school she also doesn't go to the point I don't tell her I won't be in tomorrow so she would just go. Almost every activity she does has to involve me or she just doesn't want to do it. I should really importantly mention she comes from a pretty abusive family to the point Im so fucking sure if she moves away from them she will geniunly fix herself completly and beside of that she grew with a lot of sibling while I'm an only child so she is def not used to being left alone. But I'm just so sick of feeling like a nanny instead of a friend, Im fully serioures when I say she is the stereotype of non-medicaded adhd she always goes from a 0 to 100 out of nowhere and I cannot for the love of me make her stop and she only listens when she wants to, shes very ignorant to her surrandings whice from time to time costed her trouble THAT I had to fix and she doesn't care about a lot of important things. And whenever I say these things she always says how "people don't care blablablabla" And I CAN'T just end the friendship and I don't really know if I even want to bc the story im telling is just the tip of the iceberg it would be a rlly RLLY long post if I typed all of it in detail, I rlly do like hanging out with her when she is more normal and not always with me but I just want her to quite down and stop being so depended on me. How do I tell her this?? What do I do?? If I end my friendship she might even stop going to school and everyone knows me as her friend. Please some advice!!