There were a lot of possible responses, but the slap was what happened. It's great that he cares for his wife, and the joke wasn't appropriate. However, violence isn't necessarily the answer, and I don't know how it just came to that.
Honestly I thought it was a joke too. I really didn't put too much thought into it. I would not have even known the Oscars were on until I read about this the next day. I heard he was suspended for 10 years now.