How do I move on without my dog?

This week I made the worst mistake I've ever made in my life. It started out as a late bike ride and I will feel the stupidest person alive for trying to ride a bike now at 7:30 but that's what I did. My dog, my best friend, that helped me get through so much in the past year, got out of the gate because he wanted to come with me. I tried to stop him and block him while I was getting my bike out the gate opening but he dodged me and ran out into the street and now I know I had let him go right in front of me, its the worst feeling I've ever felt. I chased him in neighbor's yards but he though I was playing with him so he kept running further and further out into the street. I felt helpless and it kept getting darker but then he passed into the highway and I kept panicking and stood there hoping he would see me. I never thought he would get killed because he had the most amazing spirit I've ever seen in a dog and all I keep thinking about is what I should have done to get him back and I know I could have saved him by running in the opposite direction. He always followed me and I am afraid that truth is never going to go away and will always haunt me over his death. It felt unreal seeing him killed and then lifeless on the pavement and I still want to believe it never happened but I know it has because now I am never going to see him run to me again. People keep telling me its not my fault but I know they are just being nice. Everyone in my family knows I am responsible for his death and that's what hurts the most even though they claim that my life is more valuable to them than his. I don't want to think this as an obstacle or lesson to learn from. I just want him here with me!!!I I want him to know that I loved him more than he ever knew and hug him with everything I have because he really was my best friend. I took that for granted so much and I can't ever take what I did back no matter how much I try. My conscience is tormented with thoughts what I should have done. I could have put him up in the house, I could have ran the other way so he would run after me(he always wanted to win every race..), I could have tied him up and never leave that spot, I could have gotton the hula-hoop and chased him away from the gate(it was the only thing he was afraid of) or I could have asked for help. But it doesn't matter because he's dead and I can never see him looking back at me and bolt in a second like a big horse where I was every time I stepped foot in that yard and now..he's buried there. It hurts to go in the backyard, front yard and i can't face riding my bike on that street without ever knowing that's the reason he is dead now. I'm trapped.I will never see his irresistible face panting back at me like he just ran a marathon and then collapse on the floor. Everything about him was so lovable and I didn't love him half as much as I should have and I am not just saying that because he is dead. He was neglected sometimes being alone in that big yard. I used to run with him at nights and that was biggest moments of freedom I have ever felt him being there with me. I should have ran with him more. I don't care if he won each race and strut himself all around me. He was beautiful and everyone knew it. I feel so ungrateful all the times he was there. The times when I was mad at him just for being who he was. He probably understood me more than anybody because really he was just - like - me. Stubborn, competetive, playful, aggressive, my mom would always say that. Almost everything about that dog was a part of me. We were both retards but I will never see him again - only memories.. All because of one stupid mistake. I never wanted to hurt him, he was mine. I didn't care at the time if something happened to me but not him. The only friend that followed to the death because he loved me that much. I don't want this. And I don't want to be me right now. Probably not ever. Its not worth being me for what I have done because I think I can't stop being afraid anymore. I don't know how to move on much less how to live with this. I was already going through depression but now it feels its always on my back literally 24/7 and I wont' let me go. It affects everything I do. I am homeschooled and I stay at home all day so I really can't forget seeing that empty space where his cage used to be. Everything is staring me in the face and I can't do anything about it. I don't know what to do. I never thought about suicide and I don't think I ever could have the guts to kill myself but I do know that I would be better off there. Then I would not have to feel and have all these thoughts running through my head relentlessly. At least I would be where he was. dead. I feel abnormal because I can talk and write about it and hardly shed a tear but a certain word or thought makes me cry in intense spurts. My life really doesn't seem wor