I'm a 15 year old boy. So I recently met this girl named Sarah and let me tell you, she's goregous and amazingly beautiful. We're both 15. When we first started talking she was in a 11 month relationship so I tried not flirting with her or showing any interest in her that would make her think I liked her more than a friend. Her boyfriend was a real jerk to her so she would come to me crying and asking me for advice. I tried helping the best I could and she realized I liked her. The next day her boyfriend broke up with her and told her he hated her. Later that day we were talking and she noticed there was something on my mind that I was keeping something from her. She kissed me and said she liked me too. After that things were going great, we were with each other all the time and I would wake up thinking of her and fall asleep thinking of her. Then today, 2 weeks later, she told me she liked another boy. I was crushed because just the night before she told me she loved me. I couldn't believe it and I was so badly hurt and angry because I thought I really fell in love with her. So I started punching the walls and all this anger and rage builded up inside me. I realized that I was just the rebound, that she couldve used me to get over her ex, do you believe so? Do you think she only used me?:confused::confused::confused::(:(:(

I don't think she deliberately used you, but you were in the right place when she needed someone to talk with and help her work through her upset (or, more likely, get her mind off her ex). If she hasn't worked through the break with her ex, this boyfriend isn't going to fare much better than you did. She may go through a whole bunch of bfs before she gets herself together, if she ever does. The best thing she could do right now is swear off relationships until she gets her own head on straight. She needs constant validation by someone so she can believe she is loved. She must go back to Square One and learn how to love herself first so she can love someone else.

I'm sorry this happened to you.

Lesson #1 -- Don't become someone's rebound boyfriend.

Yep, she used you (although not intentionally) and you took advantage of her vulnerability ( not intentionally)
This is why hooking up so soon after break ups don't work.
Sorry this happened, but take it as a lesson learned.