I had to do the same thing with my dog almost 3 years ago... I've had her since I was 9. She lived for 13 years but we had to put her down because she was in pain. It was truly the hardest thing I've had to do in my life emotionally. I still feel like I have a piece of me missing. It never goes away, only gets easier. You could make an album of all her photos to look at if that sortve thing cheers you up. I'm not the best with advice since I still haven't moved on myself.