re: Have to put down the first dog I ever owned.

You made the right call being there. When I had to put our dog down a few years ago I was there and petting him as he faded peacefully. It was hard but comforting to be there for him.

And as someone said above, just take comfort in the fact that you provided her with a good home and love for those years. For mine, he was found as a small puppy starving on the porch of an abandoned building next to one I was working in. So I took him and it was good knowing we gave him a great life.