Is a safeword too much to ask for? And in any case, 'stop' seemed liike a pretty darn obvi...

Is a safeword too much to ask for? And in any case, 'stop' seemed liike a pretty darn obvious red light to me. If you want to add insane scenes like this, it's not hard to make it so that the bottom is enjoying it. It's your story, no need to turn it into assault