Murder Motivated by Love

I just killed a spider. I probably didn't have to. I could have caught it, let it loose outside, and let it live. If I had been the one who found it, that's probably what I would have done. But I didn't. I killed the spider, even though I didn't have to. Essentially, I murdered the spider.

Yet, I killed the spider out of love, not for the spider, but for my sister. She was the one who found the spider. She fears and/or hates spiders (I'm not sure which term she prefers), so I made certain that that particular spider could never bother her, or anyone else, ever again.

Is it wrong to kill a living creature when you don't have to? Almost certainly. Is it good to act in accordance to one's brotherly love of one's family? Also yes. So, then, what am I to make of my decision to kill a creature for my sister's sake? I don't know.

Thankfully, that act was probably not significant enough to matter much, in the grand scheme of things. Still, I'm glad I'm not the one who needs to judge my actions. I have no idea how to adjudicate the proper reward or punishment for someone who kills a spider as motivated by brotherly love.