How do I (15M) even move on from someone I don't even know (17F)?

So ok basically I've already made another post here about this girl but I'll re-explain. So basically: I'm in High-school. I'm in 10th grade, and I've been having a (probably) unhealthy obsession with this girl that's in 12th grade for almost a year now. Since it pretty much started when I got into High-school, a year ago. So the post I've made was like maybe 2 weeks ago during the summer break, but I just started again. Today was my first day of school, and it reminded me of how bad my obsession is. Like I was at the Tim Hortons at the other end if the street in front of my school with my friends (for those who don't know it's a Canadian fast food restaurant). And I was casually waiting at our table since I had ordered on the app, and the girl arrived with her friend group. And just the fact she was waiting behind my friend group and sat at the table next to us, drove me crazy that because I can't talk to her. That's how bad this is. And it's just super weird because I don't even knoe this girl. I mean I know people do have crushes on people they don't know, but for me it's my first time having one on someone I don't know. Especially this bad. The closest thing I've had to an interaction with her is one time she smiled at me, and I honestly don't even know if she was actually smiling at me.

I could talk to her. And I do have a friend that knows her well, but I've came to the conclusion that it's a bad idea. I think it will just feed into my obsession even more and will just make it worse since she's 2 years older than me, and probably won't like me back. Plus she will (probably) go to college in like a year. I also know that by the time I work the courage up to get to know her, and eventually ask her out on a date, it will probably be too late. The age gap is not problematic IMO, but in my situation I think it is problematic for me. If I actually wanted to get to know her and ask her out, I should've done it last year. It's too late now. I also know how much time it takes me to move on. And fuck man, she's way too pretty for me. She's really way out of my league. I'm like just this nerdy guy who wears glasses (well ok I guess that's irrelevant she wears glasses too), and she's like honestly the prettiest girl I've ever seen in my entire life she's probably the closest thing to a 10/10 I've ever saw appearance wise. I genuinely don't mean this in a weird way, she's just wow. It's the truth. And I know it's a huge danger for me because I'm scared I would put her on a pedestal. And it's probably one of the most dangerous thing you can do for your mental health as a guy.

I mean sur my best friend (who's in 11th) has a GF who just started college. But I don't see how a relationship between a high schooler and a person in college can work. And I'm not even saying that to be negative or a jerk about my friend, but it's just the truth (I haven't told him that tho). I think it will be hard for my best friend and his GF, and I will be there to support him if things go bad.

So essentially my question is: How do I move on from someone I don't even know and I know I can't have?