blackmail
I'll create an automated tumblr post w/ the information that is set to go out every night at midnight [unless I stop it] in case said person tries to kill me too.

EDIT: I realize this will make me an accessory to the murder so to convince the authorities otherwise if said person is caught, I will say that I was forced to keep my mouth shut bc he/she threatened me and my family's life.

I watch a lot of crime dramas.

Rushing to call the police without any evidence would be a mistake because why would they believe me? It'd be my word against my friend's the murderer, and if he/her finds out I tried to blow the whistle I would probably be the next victim

I would encourage them to turn themselves in.

If they didn't, I would then call the police.

Hell no. If it was close family I would just swiftly brush it under the rug. If it was a friend I would literally fly to the police.

I'd probably call because idk if they're mentally unstable and would later kill me because I knew what they did.

I'd get FAR away from them and then call the police

I'd forget by the third night and then me and the killer's asses would both be doing time

Depends on who it is. If its my mom, significant other or any of my siblings no, but a high school friend or acquaintance then bye

Phone the police.

I would turn my friends or family in ASAP.

If it was Halsey or Gaga I would never. They are the only exceptions. I don't even stan Gaga but let's be real here...

If it's a hot guy, lock him in the basement. If not, call the police.

I've not into having any more freaks as friends so I would probably just get as far away as possible.

idc

Not my damn mess and I ain't about to make it one.

That's cute girl, keep it ALL the way moving, next subject.

Honestly no one can answer this until they're in that situation. However I probably wouldn't tell if it was a family member, and probably not even a friend. I'm not the one to tell, and no one's actions are my problems.