I can't belive what i found out... crazy. shall i finish it?

I Would ask the "friend" if there was anyone else who heard/saw it. You Said that she told 'everyone in the room' so that means there must have been someone else that you can talk to about it. If anyone else says the same thing, you should confrunt your 'girlfriend' about the situation and what you have been hearing, but dont make it seem as if your jumping to conclusions, Just say to her "Look a couple of your fiends have been saying... I didnt know what to do so i thought i would talk to you aboout it" But try not to mention any names. Depending on what she says depends on what you should do :)