Sometimes we may individually feel that the only choices left to us are bad choices (Killing, or being killed, for instance). That happens, you make a choice and accept the consequences of having made a bad choice. You don't need to "justify" that your actions were somehow good and desirous. In fact the only real benefit to making a bad choice is in acknowledging that it was a bad choice with bad outcomes, otherwise it becomes a choice that doesn't seem so bad. When bad choices seem less bad, they are more easily made, more often, with less of a need to consider, regret or justify.
Accepting that you occasionally make bad choices with bad consequences helps you to keep from ever developing the mindset that a bad decision is a good or desirous choice to make. Any decision that results in death is a bad decision, sometimes we choose to live with bad decisions, that does not make the decision good, or the outcome (a death) desirous.