[17M] She[18F] friend-zoned me as a "brother" but sends flirty reels. I'm catching feelings and it's ruining my studies. How do I detach?

I am a 17-M. I’ve never had a girlfriend before and generally kept to myself. Recently, a girl 18-F entered my life who had just gone through a breakup a few days prior.

We started talking, and after only three days, she asked me to be her "brother." Since then, she treats me like a therapist she is constantly venting about her ex and expressing her unresolved feelings for him. I always listen carefully and try to be supportive.

Here is the confusing part:

• She texts me almost every day.
• She often sends me reels that are a little bit flirty or romantic, which sends mixed signals.
• I’ve started to really like her, even though I know I shouldn't.

The Problem: I feel emotionally invested even though I know there is no future with her (since she still loves her ex and sees me as a brother). Before this, I barely checked my Instagram DMs. Now, I find myself constantly waiting for her texts. I’m wasting hours checking my phone, and it is seriously hampering my studies.

My Goal: I want to keep talking to her because I enjoy the friendship, but I need to stop feeling emotionally connected/invested so I can focus on my life and grades again.

How do I stop obsessing over her notifications while maintaining the friendship? Is it even possible to stay friends without getting hurt in this situation?(if possible i want to take advantage of this situation so that i wont have to become a victim later)