Best way to euthanize hen

[Ljc01]

This hen has had nothing but health problems for months. She has been having seizures, which have stopped, but her neck is twisted badly. The other hens are now picking on her. The worst part is she can not roost anymore, seems she has no strength in her legs, so she is hanging out in the nesting box and pooping in said box.
I need to euthanize her, but I am such a wimp about doing this and my DH is of no help!
What is the best way to euthanize this hen, for both of us. Quick for her and painless for me!

 

[Kiki]

Slitting the neck with a sharp sharp knife.

 

[tastyacres]

Slitting the neck with a sharp sharp knife.

2x

 

[andreanar]

You can look up the way to do it with dry ice.