Did you really want him to stop? If so... it seems you have neglected to discuss how to stop a scene.

Go look at the safeword threads. Even if you never use it, knowing you have it may change how you perceive new activities.

As far as face slapping goes, some love it . Some hate it. But I think everyone changes their perspective after they've experienced it a few times.

Nothing wrong with feeling unsettled. It's when you're least sure of yourself that you are the most appealing... taking your discomfort for our pleasure.