I'm a Hero?

This is a new experience. I'm exhilarated, fascinated, and feel good about my deeds today. I also feel sorrow, disgust, and ashamed of my deeds today. I literally blasted an individuals head open today. Three individuals took over the train and caused it to run too fast and shoot past our destination. Between that and the railcars heating up it could have killed everyone on board. We managed to reverse the environmental controls and force our way into the next car. The Tiefling that later introduced himself as Jaxion almost flew out the open railcar door as well as a few passengers. Once Jaxion was back inside I managed to mend a door back in place to keep anyone else from flying out as long as they stayed strapped in. I injured the unhinged individual that seemed delighted that he was inflicting mental and physical anguish on the passengers of this railcar.
 
With the help of Jaxion and Lux, we chased the individual to the outside of the the engine car where another individual was waiting. Lux was hurt but we managed to eliminate the unhinged individual. The other had a jetpack and tried to fly off, but Jaxion grabbed him and threw him to the ground. On his way down I shot him right in the face, exploding most of his head. My first kill. I'm equally exhilarated and disgusted. Did this individual deserve to be killed? He had intent to kill us. He broke laws and if not stopped could have killed everyone on the train. I broke no laws killing him and he would have rotted in a prison or been executed for his crimes anyways. Things to ponder in the days ahead.
 
There was another individual in the engine compartment. He seemed to be their leader. He instantly reminded me of the villains from the western shows. Maybe that is why I acted quickly and my aim was true. I jumped into the car with Jaxion and unloaded a shot right in his chest. Jaxion looked sturdier than me so I protected myself from harm, only to find out they were after me and didn't want to kill me. I also didn't realize that one round would instantly down Jaxion. It was a powerful weapon so maybe my assessment wasn't incorrect and it was just bad luck. Will need further data. Lux came in and healed Jaxion while my second shot struck true again. This time moving my protection to Lux so he had to focus on me. To my surprise, and his it seems, Lux had another trick up her sleeve and deal the final blow.
 
All in all my aim was above standards today and my strategy flawless. Individuals thanked me and Dr. Topip praised me, but I still feel a bit conflicted. Am I a hero?