I understand why you feel bad for feeding live but it probably was a mistake to take it away at that point and it could have been dangerour for your snake. It would have been upsetting for you had its jaw been injured all because of one pinkie mouse. But I do understand how you feel.
I would say just don't fed live, don't buy snakes that need live a lot and don't interfer with the feeding again.
Good luck in the future. As you keep snakes for longer and longer you WILL be de-sensitzed (sP) and you will know that sometimes its better to leave things alone rather than giving human intervention.
Four or so years ago I had no snakes. I certainly had no clue about the whole "mouse world" out there for rodents. My BF wanted a snake so he got one. Here we are four years later and last night I just cut open a pinky head to get a hatchling snake to eat. Four years ago this would have made me sick, it would have made me feel cruel and really horrible. I didn't even think twice about it last night.
As your interest grows for snakes, your sensitivities for mice will go down. You will see them more and more and more like food each week. Not to say you won't care about suffering but things will get WAY easier for you.