That is nonsense.. That's actually kind of metagaming in my opinion, atleast how you explain it now. You don't CK them because they're your friends? That would be weird. Sometimes stories happen with these ends.. If it's your friend or not.. I mean, it's not for fun to do yeah but well.. Sometimes, sometimes.. And if he doesn't roleplay with you anymore because of that that says more about him than you sadly. However I can understand if he wants to take a new project after getting CKed. I mean, I don't think many will rejoin if they get cked xD
Well kinda harsh to say like you "all". I mean, I think everyone have felt emotions by a game. People who say they don't aren't robots they are just to tough to tell the truth lol. And feeling emotions isn't immediatly shouting and raging. But it can be a simple form of being annoyed. I remember about ten years ago me being in a roleplay scene which didn't work out so well me ending up in smashing my pc broken, lol. Of course that's not the way to go, but just a brief example. I was still a kid back there but still..
So conclusion, I understand you have feelings about killing a close friend, who wouldn't, people who don't are just badasses. Serials lmaooo.