What to do when you're grieving over your best friend?

Sweetie, there will only be one Roxy. In my lifetime I have had one special cat and one special dog even though dozens have lived with me. I never replaced those two special ones. You can't. And adopting a new puppy now would be a disservice to it and the owner it will need you to be. There will be moments throughout your entire life that you will think of Roxy. And that thought may bring a tear or a smile. But you will, in your own time, learn to deal with it. Perhaps your not being there was the best thing. I am an emergency and primary care vet tech. I have given the "it's the best thing for your pet" speech a hundred times. Up until my seventeen year old dog last year I never had to make the decision for them. They had always decided when to leave. But I had to for DB and the tech and Dr gave me the same speech. You know what? I didn't hear a word they said. Because this was MY best friend and I had to let him go. Having that life slip from your hands is not something the average 13 year old is prepared to deal with. And, if you weren't going to be in the room, then the last memories of Roxy alive and active are the best ones for you to have. I'm sure your mom wanted to make it as easy as possible on you. When we grow up and our lives start to encomp more things like bills, jobs and raising kids, we sometimes push aside those things that were once so important to us. Your mom probably tells you to "get over it" because that's what she may have to do for the sake of her family. It doesn't mean that she doesn't want to understand. For a time you had a very special friend in your life. You adopted her in her later years and made her life the better for it. While she was with you she felt loved. Don't think for a moment that she thought any less of you on her last day. Someday you may be fortunate enough to have another pet choose you. But if you spend your time focusing on what was you'll completely miss what is.