How to cope with death of dog

So my moms dog, that I loved and cared for so much had died. 3 days ago and I found out yesterday. I loved this dog more than any animal I ever been around or had. I think I always been so attached as if my own because we had to take care of him several times for months at a times because my mom went through a lot of things. She loved him so much and he’s been through so much with her so I can’t imagine how she feels if I feel this bad. Her friend was watching him for her while she served time which he has dogs of his own. I couldn’t take him this time due to me recently moving and my complex don’t allow dogs. The person who currently was taking care of him had a stroke and can’t walk so he’s in a wheel chair and would take him out on a leash. Our poor little baby ran out too fast and he couldn’t stop him in time and ran straight out in the road and got ran over. I can’t deal with this I haven’t accepted his death and I don’t know how. I can’t believe he’s dead and gone forever and I’ll never see him ever again I keep crying over and over. Everything reminds me of him that’s a messed up way for him to die. I keep picturing how it could have looked and how painful that had to feel his tiny little body being crushed... I feel so sick inside...please any suggestions how I can feel better and not think this way. All I can think of his pain he had to feel that hard and how I’ll never see him run to me and jump up with his cute tiny paws and how he was only three years old...didn’t even get to live long..he had the best personality...way to special to just be dead...now bugs are probably eating at his body in the ground I think it’s so wrong and messed up I miss him I wish I never got so attached. How do I deal with this?