You're young so I don't think your a complete POS for this, just inexperienced but...come on, dude.

A.) you didn't get "friend zoned". She simply isn't into you romantically but she thought you were a good guy & wanted to be your friend. That's a thing that will happen in life sometimes & women absolutely hate it when men just act like a friend because they hope they can be more some day. Seriously, don't do that.

B.) if you have to hold out hope that a person will date you eventually, just stop. Anybody that will date you will make it obvious that they like you. If a girl wants to date you, she's not going to tell you no one day then change her mind later. I made this same mistake when I was younger as I'm sure a lot of guys do, but seriously you're just setting yourself up for disappointment if you try to convince yourself you have a chance with someone that isn't interested.

C.) Don't ever use someone else's phone without their permission. You know that you fucked up by pretending to be her & texting that guy but you need to understand that you really fucked up the second that you touched her phone without her knowledge.

I think you should really reflect on what you did & focus on doing better in the future. I know you want a girlfriend & probably feel insecure about the fact that you don't have one but you're obviously cool enough to have female friends, so if you just chill the fuck out you'll eventually meet some that want to be with you as more than friends. YOU WILL KNOW when you meet that person, I guarantee you.