My confusion and me... Please help

Hello, i am a teacher so my problem is one of my students acts weird mm mm how should I explain it.
Well i'm   a 23 years old teacher my intention was always help kids to find theither way so I been doing that helping them
one day one kid I always helping told me "Miss you should look at her closely.. she's   not what it is"
His words were on point she wasn't   what I thought she was a lonely girl with a boyfriend who breaks her heart she is 16 and her boyfriend 21, she lives alone and her mother is travelling so I notice that she had a little obsession with her boyfriend to not be alone , if he wants money she sells whatever she has, he likes skinny   girls  she doesn't   eat for days so I became closer to help her (now she's better eating and has friend before meeting me she didn't   speak with anyone cause her bf get mad) now we chat all day long, she tells me things like she loves her boyfriend but she tells me things like you are so pretty , perfect , flawless if we don'the chat one day she'll   get worried, she makes sure if I eat or take medicine, she gets jealous because I help other kids ... really mad  to tell me that I forget about her and everyone is first and stuff like that, lately I been thinking a lot abut her don't   know what to do I have my Bf   too   but I keep thinking about her. Now she has found the way to scape from class and go visit me to other classroom   and stays there watching me while I teach other kids.
I know maybe she sees me as a mother figure but I remember once I was with one of my friends and she text me things "i'my not cheating on u. You are the only one i'my talking to with many hearts" my friend asked me of we were dating
she confuses me with her messages "She can't   share me " once I told her another kid was cutting herself I was trying to help him and stop him "She said fine i'Ll share  you a bit" seriously   don'the know what to do, if I leave her I think she will be back   to the bad habits so if I stay I get hurt..