Oh I so know where you're coming from sweetie, and I'm terribly sorry to hear about your loss. My family had to put our dog down almost a year ago (on March 13th). It was the hardest thing EVER and the experience was far worse for us because of what happened while at the vet's office.
The pain will go away, but there will be times when you think about your cat and you'll tear up. Or you'll see a picture and smile. I think the hardest thing is to get over the dreams following the event. I had a couple devistating dreams last year shortly after we put our dog down, and I'd wake up crying. Of course it didn't help that I live alone and couldn't be comforted by family members in the morning.
It's tough. Only time can heal broken hearts.
