1. You need to love yourself, and you really need to appreciate yourself.
2. From what I have read, you find her to be pretty. I don't want sound rude, though you might find her to pretty, but not everyone might find her pretty. For instance - There are people in this world that find Anjelina Jolie to be hot, while there are other people that do not find her hot at all. I guess that is a very bad example, but do you get my point? Similarly, there might be people out there, who might find you very pretty, and there are people who might not. But, I think more than how you look is how you are as a person.
3. This girl could look beautiful, she could have a million friends, and look perfect to you, but possibly beyond that she finds herself to be lonely (there are people out there with this problem, many friends, yet they seem to be lonely). She has 200 friends, and you have only 30 friends on Facebook does not necessarily suggest its all perfect for her. Maybe she just adds everyone she knows, or maybe people just add her, as opposed to you, who only adds close friends. I'm trying to point out that not everything might be perfect in her world, but anyway I think instead of looking at her; you should take a look at your life, and trust me there are people out there, who have to deal with even bigger problems. Sometimes when I look at them, I realize my problem is virtually nothing, and that somehow helps me appreciate my life a lot more. Try that. Remind yourself daily that things could be a lot more difficult for you.
4. If she deleted you, then she lost out on an amazing friend! :) :)
5. You need to really boost your confidence, maybe point out to yourself, that you are doing well academically or something else. To be frank with you, a few years from now its not going to matter to you, who was more social and outgoing.