Definitly agreed ! People need to get over the fact that sometimes their favourite characters are horrible person, murderers, mean, racist, whathaveyou ! So what ? They're fictionnal characters, it's OKAY to love a fictionnal character even if they have big moral flaws. Think of it as unconditionnal love ^^

The interesting thing in Severus, Regulus and Draco is the gray area. If you appologize them all, you're only left with a shade of the character. No fun.

I very much doubt Severus never killed anyone but Dumbledore. I even doubt it for Regulus, because he'd have needed time after taking his decision to investigate Voldemort's properly to know even about one horcrux.