Answer:
I say revenge isn't worth it.
I don't want to be all political and stuff, but it sure isn't worth it.
Revenge is sometimes a pretty good thought, your best friend gets killed? Don't kill who killed your friend, for you will also be breaking several rules. Murder is illegal and so is murdering a murder, unless you are an executor in jail. Anyway, if you kill someone, somebody might want to kill you as well, it is an infinite reaction. You kill someone, someone tries to kill you and so on.
Number 2, if you manage to avenge your friends death, you would have to deal with the fact you killed someone, someone who actually had people for them, you would have killed another human.
Step-by-step explanation:
Revenge is never the best choice, leave it to the authorities to take them out or send them to jail.