I'm still in love with my ex.?

Me and my boyfriend broke up about a month ago. For me it's been pretty life altering, to say the least. We were together, on and off, for about 4 years. He was the first person I fell in love with, first person I had sex with. He was my first for a lot of things I guess. So this is all so strange and painful and scary to me. It didn't hit for a week or two. I guess, I was still kinda in shock I think. My friends and family were always asking me how I was, and I just kept saying fine. But I'm not. I never was. Looking back, I can't believe I said I was fine when there were so many signs that I wasn't. I have to physically keep myself busy and moving at all times in order to keep him out of my head. The smallest memory breaks my heart all over again. I've never been dramatic or even a very emotional person. But this is just killing me! I know it's weird and everything but...I still feel like we're supposed to be together, like..meant to be. I can't help but feel he's the only one for me, and always will be. I love him so much, it hurts. My sister mentioned another girl in her class that liked him and I felt sick just thinking about him with another girl, even though I know he wouldn't do that to me. I don't get it, I'm just so lost and confused by all this and how he's reacting to our break up. From what his friends and my friends tell me he's gotten a lot more quiet and shut down and depressed looking. He's angry looking a lot of people say, when he's usually a cheery smiley guy. When we see each other, he looks very upset and I just want to touch him, kiss him. Anything. I'd even settle for a hug! Just something to know I'm not alone in this nightmare! I can't sleep very well. I think I have insomnia. I haven't slept a full nights rest since the night of our break up. I try! So hard too, because I just want to shut my brain off, so I won't think about it and him. But something keeps me awake. Another thing is even for a tiny girl as myself I've always loved eating and I eat a lot, but whenever I see him I can't upset stomachs and can't finish whatever I'm eating. I seriously have lost my appetite like 3 times. It's hard to smile, laugh, think, concentrate on anything but him. I hate this feeling in me, like a dead end. I know everyone says this, but I don't think I'll ever fully get over him, or fully recover. 4 years is a long time. And we made so many plans and promises. And I know, without a doubt, he loved me very much too. I still wanna believe he's in love with me still...but I just don't know anymore. Can anyone help me? I'm dying here. I can't make it go away...but how do I numb or dull this pain..?