Hi heather, i'm so sorry to hear about snowflake and i hope that there is some miracle and you get to spend a bit more time with her.
we had to have my collie, sunny, put to sleep about 11 years ago and no you never forget them and all the happy funny memories, but please believe that the raw pain of losing them does get better.
I was at the vets when Sunny was put to sleep and sat on the floor with his head in my lap, i remember the vet saying to me that alot of 'humans' dont get to live the sort of life that a well loved and cared for dog does, and that many 'people' dont get the opportunity to die surrounded by people they love. I know her saying this helped me a little bit.
Just remember all those happy times and know that you contributed greatly to making a little dogs life very happy and special.