This was a tough thread to read, but an important one, I believe. We have to be reminded that along with the joys of owning these wonderful creatures comes the painful responsibility of having to make decisions like this. It is times like this when we have to put the animal's pain/suffering ahead of our own and do what is right for them.
Hon, I believe you absolutely did the right thing...and all throughout the little gecko's life, you did the very best that could be done for her. Though it may have been short, her life was filled with warmth, security, and good food...which is heaven for them.