I have a question, and need an answer...?

the other day i was called out to a situation, i'm an MP (military policeman) and i was at a call, domestic disturbance, a man had multiple weapons in the home and SRT (military swat) was called to handle it. i was set as an MO with a long rifle and told if i see him with gun in hand and looks if going to fire, to drop him. so there i was laying prone, cross hairs on his head, then it hit me... i was scared, i didn't want to kill this man, not because i am a coward, but because i enjoyed the feeling i was feeling.. i had the power to end it in a second... well, the man gave up easy and no shots were fired.. my question is, can there be a good evil? God has allowed things to happen what would seem evil.. can i like the feeling, but still be a good man?