How do you get over having to hurt the ones that you love?

The idea that one must suffer pain to stop feeling more pain is lost on most children. You have to sit down and discuss it. To know that you are in just as much pain as they are with having to hurt them in anyway might help. Explain that in as simple of terms as you can and just remind him that you love him. That they are your reason for living and them in pain is the last thing you want. It is the one thing you are put on this earth to prevent and that the pain they are feeling now is to prevent any future pain. It isn't going to be perfect and it isn't going to be easy but love will always win out.