Breaking Heart...Am I Being Selfish?

One of my absolute closest guyfriends has just recently gotten involved in a "relationship" with some other girl from his church/youth group. He always seemed to have special feelings toward me, because he would favor me over practically every other guy or girl around. He and I bonded quickly from the moment we met, and honestly, I was hoping our relationship would have turned out to be something more in the future. I know this probably all sounds cliche, but the girl he's apparently "fallen in love with" even looks similar to me, except I'm more tan and curvy in figure than herself. But, other than that, we both wear glasses occasionally, have bright eyes and rounded faces, etc. I didn't want to get involved in a relationship as yet, because I'm still a teen and know that I have know concept of actually being in love, but I thought he could see just how much he meant to me as a loving friend. I'm absolutely heartbroken now...especially seeing how incredibly happy he is with her (her name is Jackie). He's texting her constantly, straight after school ends for the day. My other friend, Nate, said that when Nolan's not with Jackie, he's either texting her or on the phone with her. Yes, I want him to be happy, and I'm happy to see him smile so brightly now every day, but deep down, I really wanted him to be happy with me. Am I being selfish for having these feelings? I'm not (and will never be) the type of girl to break apart a relationship, but the feeling of betrayal and jealousy is extremely dominant in my emotions towards him right now. Any advice would be helpful. Thanks :) <3