Losing best friend

Recently my best friend seems to be distancing himself from me. I have tried to start a conversation but he usually just gives short answers and goes back to doing whatever he was doing. We still hang out usually about once a week but in public he just seems to uninterested. It's making me really depressed and I feel like I'm going crazy. It's just he was such a great friend before. It mainly started after I recovered somewhat from my depression. I started going to him with personal problems related to my depression disorder in which he helped me tremendously . He helped me out alot and I was really grateful for him. I love him and I really don't want to lose him. I'm losing sleep, can't concentrate in school, and not eating much over it. Any suggestions would be appreciated. I try to approach him about it and he just gets defensive. I think it's literally driving me crazy and it's driving me back into a deep depression, except this time I don't have a best friend to be there for me.
I really don't have any other real friends. Just aquaintances. I sorta tried to start making some new friends but my heart really isn't into it. My mind is just too occupied on being depressed. I always try to keep my mind occupied and it sometimes works for awhile but my mind always goes back to being depressed and how great I felt when my friend would give me a hug or hold me when I was crying or would promise me that he would always be there for me. God it kills me just thinking about it. I asked to see if he would talk to me for 5 minutes the other day and he got really upset at me. He wouldn't talk to me at first and I finally had to tell him this story about how I thought I was going insane the night before. He told me that if I thought I was going insane I should go to the emergency room and that he just wants to worry about himself now. It's really killing me. It's my fault for taking all the comfort he was giving me for granted. Now it's all gone and I can't even get up to go to school. Lots of the teachers just think I'm faking sick so I tend to get on their bad list and I have rehearsals after school that I'm not aloud to go to if I miss school which is bad because I have a huge role and I'm supposed to design the lights for it. I can't take it all I really can't. I don't know what to do

Something's really wrong with your friend. I can't say what. Maybe you can get an acquaintance to talk to him for you? I have no idea, but I'm really sorry you're going through this.

i wouldnt try to evaluate ur friendship to much while ur depressed, because u can make things look different to how they really are when ur depressed. when i was 15 i was deeply depressed, and my friends were there for me. do u know what drove them away? it was me wanting constant re-assurence that they cared and were in fact my friends. at the time i felt like they didnt like me, even tho i was with em all the time. now looking back i can see they did like me, we eventually fell out because is was exhausting the friendship by me being TOO needy, because theres only so much a friend can take of our personal problems before they get tired. we did tho make up after i sorted myself out. were still mates now and im 20.
i would, next time u see them, dont mention ur depression wot so ever, just try and muck about , like mates do, maybe hes just gettin abit bogged down by ur problems, not that he dont care, coz even family can grow tired of our problems, but maybe he needs a break from ur problems, and just wants to enjoy your company instead.

I wish I had a friend like you that cared like that