Keep in mind that the accuser never called the police or her parents. Obviously I don't know how the scenario played out, but to me it looks like this...
Winston and girl do something not very classy, but common among college students, of a random hookup. Girl had literally just been with her boyfriend.
By way of explanation, girl tells an untrue story to roommate.
Roommate, against the accuser's wishes, calls the police and the accuser's parents, and it's off to the races.
I really don't think the accuser ever intended to pursue this, I think she said something kind of dumb without really thinking about it, and it ended up getting away from her. I feel horribly for her, because even though I don't think it's likely she was raped, I do think her life has been totally ruined by the actions of a definitely well meaning friend, and a family lawyer who may or may not be all that well-meaning.