I'm so sorry to hear about this situation. This slapping, fighting and disparaging behaviour is totally unacceptable.

So, there is an anger problem here. There are boundary issues. There is a lot of reactivity and neither of you are keeping your cool.

When things get tense, you will need to try to de-escalate the anger and tension. That could be done by leaving the room, telling him calmly that you can't speak to him while he's angry, then going in the bathroom and locking the door, or sleeping in the guestroom or on the couch.

If you get a hold of your own temper, you can also try carefully and calmly listening to what he's saying and then repeating it back to him to try to solve the problem. Let him have the last word. Don't retaliate. Don't accuse. Just let him say what he needs to say without taking it personally (hard, I know).

For example, if you calls you a *****, tells you that you're low, etc., you ask him to explain. You can tell him that you'd like to hear more about what you've done to make him think these negatives. Then you can either explain it from your side, sympathetically (tell him how you understand his viewpoint, if you say something that he doesn't agree with, let him correct you). When he's done talking, you can agree with him, just acknowledge that you understand what he said, or apologize.

You two sound like you could benefit from couple's therapy a great deal. I wish you the best.