I started to going out with my classmate, but my best friend told me , do not do that, becus, he os younger than you, Then after that I tried to do not go out with him, but still I love him, now adays I realize that my best friend is interested on him, they are flirting each other and texing each other, at first I could not believe it, but it is true. I feel really dump becus I think he move on her, what should I do. I really love that guy.

Don't say you love him because then you might think you really do and it is going to break your heart... and it sucks! Do you still talk to him at all? And just talk to your best friend and ask her what's up... Maybe she is just being flirty without it meaning anything... just maybe ask her to back off a little because you really like him... The best thing you can do is talk to her (in person) and just tell her how you are feeling... Once she see's how it is hurting you then she will might see how she has been acting an leave him alone

Good luck! :)