rat this girl the fuck out to her father and let him beat the perv's ass and put the girl on lockdown or whatever he feels need be done...
I understand she is now 18 and she's an 'adult' legally, but that doesn't mean shit mentally. She sure as hell doesn't sound like she has the mentality of an intelligent adult, and the situation is obviously bad enough that it is causing you to seriously contemplate contacting her father.
Or, just listen to everyone that says 'yea, bad shit happens, she'll be ok' and ignore the problem. It seems to me if its bearing down on your conscience now, if you don't do anything and just let her continue spiraling down, it might leave a worse feeling on you, maybe one of guilt. Maybe the father won't be able to effectively resolve the situation, but shit, you might be able to save this girl's life....
Just think if it was your daughter,,,,and how much you would appreciate someone doing this for you,,,,in the time it takes to make this thread, read all the replies, and respond to them, that one simple phone call would be very easy to make instead.
***I know this thread is a good week old, and may be too late, but it caught my attention and stood out while browsing thru the pages...(afterall, it has drugs, perverts, and alcohol in the description)