Don't ever let somebody determine your self-esteem - ever. You are more precious than all the stardust in the universe. So what if he doesn't like you? Never destroy yourself because of a stupid boy. So what if she doesn't understand how you felt? Don't change who you are because of a selfish girl.
The one that you need to look towards for strength is yourself.
Your worth is not a variable and you should never allow it to be hoisted on the shoulders of others. You've got everything you need. Accept yourself. You are beautiful.