Yes we are only human, a mistake is bound to be made no matter how hard we try to prevent them, and because of this it will teach you to pay closer attention. The mistake will lead to better care in the future. A mistake is not inherently bad, just a turning point to the better, reflect on this not as an error but a point on which to learn. When I screw up and realize it, I don't beat myself up over it as more of seeing that what is, is. Nothing can be done now, only that someone caught it on time. What is done, is done, let it be and look toward the future in the knowledge that you will do better, and in this knowledge you have become more than you once were.

I can add nothing to this. ^ I can only reiterate what has been said. Don't be so harsh. Good came of this. You have an experience where nothing bad happened, which will remind you to check twice. Use this to move forward and become better. That, also, is human...using experiences for betterment.

*offers a winghug* Release that self-doubt. Holding onto it will only weigh you down. Let it go and soar upward.