Help! Friendship troubles.?

Right now I am absolutely falling apart. I am 13 I have known this guy for 5 years now. We got on so well when we where younger and nothing was awkward. As time went on people started making fun of us thinking we liked each other when we didn't. At the end of Primary we where still friends and where going to the same intermediate. The first half of year 7 was pretty friendly, this is when things started going downhill.he started changing. Meeting people that changed him and his perspective towards me. By the end of that year we hardly talked. Last year in year 8 we didn't ever communicate, maybe occasionally on Facebook if I started the conversation. He started becoming popular. He made lots of friends, most where popular girls. He has no problem talking to them and talking to them like best friends. Now he completely avoids me. I try being nice and saying hi on face book and. Have to try a couple of times for us to have an awkward conversation. Before Christmas we had a party and him and his family and another family came over. We got on fine at this party because he wasn't with friends and he had no one else to talk to. Anyways after that we hardly talked. At college we are in the same science and form but whenever we pass we don't make eye contact. Today I was at that girls house who he met at the party and she wanted to talk to him through Facebook. She did and it was awkward. Then I said to him a few hours ago. She says hi, then he said hi. I said I'll pass you over to her and he said No I don't want to talk with you guys. That completely did it. I now know something is wrong. Have I done something to irritate him, is he too embarrassed to talk to me? What can I do to mend our friendship? Please give me some advice I'm really sad now and don't know what to do. School is tomorrow and I'm in the same classes with him. It's going to be so awkward. Please help, I would really appreciate it. Thank you.