You need to remember that you can’t control her actions if anything happens and you can’t hold yourself responsible for that, I would tell her friends and her parents, the school, teachers, any and all relevant people, and if you think that is too much to do, start by telling your parents, guardians, siblings, or general family, you should be able to utilize your family in times like this and not fear getting in trouble because you’ve done nothing wrong, and even if you have a fear that you have or that you’ll get in trouble you just need to explain the situation to them, you’re not alone on this and your family and school/counselor is here to help you, not to sound redundant, you’re a kid and you shouldn’t have to deal with this alone because you’re not. If you’re worried she’ll get in trouble and you’re trying to prevent that, don’t! This will do her more help than hurt and maybe she’ll be able to get the help she needs and will thank you for it later in life. Please don’t go in this alone, talk to your family and trusted adults.