I never kill a snake unless it is near my house AND poisonous......don't want to take a chance on my kids getting bit. Otherwise I enjoy having them around, but then again my father was the same way and instilled it in me. Growing up he would catch king snakes, grass snakes, garter snakes, basically any of the non-poisonous ones for me.......I'd keep them a while and let them go. Now days I will catch any of them.......just because I can, and they never startle me. Fear of snakes is a learned response, not a natural one.
But I do wish your wife a speedy recovery........if it were me I'd be looking for the one who bit her to see how he likes the bite of my shovel.
Regarding toxicity of the venom.........I have read the copperhead is the least deadly, the water moccasin is worse, and the rattlesnake is the worst of the pit vipers.
Here is some info on the copperhead I found:
"Equipped with long fangs curved to the back for holding onto prey, Copperheads are efficient predators but their bite is rarely deadly to human victims. Many snake bites delivered by snakes in the Copperhead family occur on the outer extremities such as hands and feet where there is little muscle tissue to absorb the envenomization. These hemotoxic snake bites usually result in severe swelling, throbbing and nausea to the victim. An effective Copperhead Antivenom exists, but is only administered as a last resort because the threat of allergic reaction is usually more dangerous to the victim than the snakebite itself. "
I believe the only snake more poisonous in the US than the rattlesnake is the coral snake.
My cousin got bit by a copperhead a few years back.......she was wearing flip flops and stepped on a small one near a flowerbed. They took her to the hospital, but no antivenom was used, and she suffered no permanent damage.
Waylan