You can stop them without ending their lives, can't you? They should answer for their crimes, but... if all you do is kill them, then all you do is make somebody else hurt too. Maybe their friends, or their family. And maybe they'll think that whoever did that to the person they care about... maybe they'll think that that person deserves to die, too.
I don't know what you've been through, but I am sorry that you've been forced to suffer like you have. You don't deserve the pain they put you through.
But... like you said, killing them won't make you feel any better, right?