Oh my...
I feel so sorry for your daughter. I'm not sure that blaming drugs will help now though. I think it is much more likely that it was a mixture of anti depressants and alcohol (which is potent on its own) along with the illegal drugs that she took. Together, that would bring out hidden sides of anyone. A friend of mine ended up in a similar situation due to just anti depressants and drink - not much, either, but the police and the hospital pointed out that the rules not to mix these aren't made up for fun. It does terrible things to the brain.
Does your daughter have a mental health consultant? If not, get in touch with the community mental health team. They'll probably see her this weekend if you are truly worried about suicide, and early next week if not. Don't mention suspecting she may have been drugged, because taking responsibility will be a big part of what they talk to her about, if my experiences are anything to go by. But it'll help her - they'll talk to her about what she remembers, help her get over what happened, teach her coping strategies and make sure that by owning her problem she knows how to stop it from ever happening again. It should help her hugely.
With regards to the tape, it is unlikely to end up online because whoever put it there would be at risk of being arrested for distributing underage pornography. That doesn't mean people at college won't see it, unfortunately. It may well be that she can't cope with going back - speak to the college about this, and see what they recommend. Moving colleges might be a good idea, but she's likely to need to let this die down anyway. At least with a small community most people will find out quickly, if they care, and it'll die down quicker.
Christmas is coming so it'll be old news soon.
Please don't blame yourself. Most teenage girls send photographs of themselves which can be distributed in a similar way - it happens. What's important now is being strong, showing your daughter how to get over this and making sure that she knows that alcohol/anti depressants and drugs are a bad combination. She really shouldn't be drinking with anti depressants, but if she does, it needs to be something very weak. Even a few cocktails can be too much.
As it was, legally, consensual, it's a difficult position for the police. They probably know from experience that its better to let it lie and wait for it to pass than to visit those involved, especially as your daughter initially thought it was rape. Stay in contact with them, and they will step in if they need too, but warning people with the tape will just make it "hot property", and much more likely to be viewed/talked about.
This will pass. Similar happened to my sister (frighteningly similar, down to the anti depressants - although no illegal drugs were involved, and the men were much, much older than her) and two friends, but they are all okay now. It's a long road but it will be okay in the end.