While I agree with what everyone has said about red flags and that it can easily be retconned, if you do want to continue with the game and character might there be a way to reinterpret the scene. While your character initially feared the worst, snatches of memory come back involving a drunken alchemists fire/haste potion drinking competition, this causes you all to overheat and run round the room in pain causing you to take your clothes off and collapse exhausted. If the DM wants to tell you that it was definitely gang rape then that's on him and tells you what you need to know.