My dog died in March but I just cant stop crying. He was everything to me, everything reminds me of him. What do I do?

We got him when I was 2. He was a rescue, his family left him in the home and someone said there was a dog barking in there. Then we got him. He hated me at first, he peed on my toys. But when I got older we were best friends. Every day when I got home he would be there and we would go up to my room and he would lay on my bed. I loved Parker more than anyone in the world. But I have 2 more dogs, Jack and Luna Bell. Still, they could never take Parker's place, ever. Plus, my sister says that I need to get over it but I never ever will. He had 1 blue eye and 1 brown eye. He had blonde hair with a white diamond on his forehead. He was 100 pounds. A husky, sharpay mix. And he was 16 years old, my best friend gone. He couldn't get any air in him, his tongue and gums were black, it was hard to look at him without crying. I have no one that understands my pain.