how wrong does this sound: anda are in a house full of vamps who havn't "drunk" for at least a month, and anda start to throw up blood

it sounds very wrong!! but remember that Edward claims to nearly be immune to the smell of Bella's blood. In Eclipse, he mentioned that nearly losing her put things into perspective, and that he can control it because he cannnot fathom losing her. This hypothetical experience would be very traumatic for Bella, but she would get through it. Edward won't let anything happen to her. :)