I went through the pain of having to have my cat put down years ago. She had contracted feline leukemia and at that time there wasn't an innoculation for it. Nor was there a cure. So, although it was the hardest thing to have to do, I knew that it was the best thing to do for her as she was very sick. Even though that was over 20 years ago, I still remember how painful it was.
You did the best thing for Stormy. You loved her so much that you were able to be strong enough to free her from her suffering. I am sure Stormy knew and knows now just how much she was loved by you. I am so sorry for your loss. In time it will be easier for you to remember her and all of the good times that was shared.
Again, I am so sorry for your loss.