intheknow, the slap is NOT the issue here. Yes, it's unacceptable, but it is only the tip of the iceberg, and a distraction from the real concerns. A's do this--they shift the focus off of themselves and onto anyone, everyone, else. You didn't cause the situation.
I see you joined here in 2009. You say he's your partner of 7 years and husband of 3--it looks like there have been problems from the start, long before this latest incident.
Please do get some legal advice. Please do stay away from him. Get to Alanon if you possibly can.
And please STOP thinking this is your fault. Although it doesn't feel like it, this could be the door opening for you to start a new and better life.