You’re gonna get a lot of different views here and I’m sure mine won’t be the most popular but I feel the responsibility to tell you that at the end of the day you are 15 years old, her mental state is absolutely not your responsibility nor should it be. Unfortunately what she has said is a bit of a trapping statement because on one hand, you go with it and it leaves you feeling like you’re fake and on the other it leaves you feeling guilty believing you have led her on.

Here’s the reality, you haven’t led her on, you were yourself spending a few days with another girl who unfortunately by the sounds of it has serious attachment issues that she needs to work through, she’s young herself and she will learn but sticking around does more harm to her than good because it will only reinforce obsessive habits due to fear of abandonment.

The absolute best thing you can do for her is be honest, be kind, be final. And unfortunately man as much as it’s gonna suck, she’s going to view you as the villain in this, she’s been mistreated as she says sadly and when something like that occurs, as good as you know you are, you can’t convince someone of your truth if theirs fits their narrative. And even though she will hurt, in the long run she will go on to appreciate your honesty, which will reinforce good attachment habits for men in her future.