A man and his girlfriend are in the elevator, and the girlfriend starts assaulting the man. What do you think would be the best course of action for the man?

Two examples I can think of in recent news are Ray Rice and Jay Z.

This question is an offshoot of this one:
http://www.fluther.com/177282/do-you-think-its-hypocritical-of-the-nfl-to-allow-ray/

The Ray Rice video is posted in the comments on the question linked.

There was a discussion about whether or not it was prudent for Ray Rice to knock his girlfriend out. Some felt it was justified, some felt not. An alternative was Jay Z. Jay Z showed a good deal of restraint in the elevator incident with his sister-in-law. I will try to find that video and post it.

Do you think if the woman throws the first punch, the man is justified in hitting her as hard as he wants to? Should the man be seen as the victim, even if he knocks her out in return? Is self defense limited to just blocking punches, or does self defense include knocking people out? Should the size and strength of the man matter?

This question is not limited to Ray Rice and/or Jay Z. You can feel free to reference them and discuss them, and/or other examples in your personal life and/or your personal opinion(s).