Don't just do something, Stand There!
...you don't have to reveal his lies or back them up. Why should you? Sometimes the best thing to do is not to do anything, be like Switzerland.... Ok, actually I hate those jerks, they cook like Germans, smoke like the French and their lameass hotels are $600/night so just be neutral.. don't be Swiss ;-)
As far as punching the walls that is scary. I think I did that a few times around age 18 when football and steroids made such a lovely combo - ridiculous upper body strength and barely contained rage being run by a teenaged boys brain? Sweet.
This is different...
Just food for thought. By the time something is bad enough for someone to take action there is usually a pattern. Problem is, until there is an incident that is bad enough, it goes unreported so folks like Lexiecat have a helluva time proving it in a courtroom.
So something to think about NOW would be to make sure that this and any future violence is documented. I would suggest seeing a marriage counselor to talk about this one. Someone who is not you and who a Court would listen to closely needs to know about this. If it was a one time loss of control and that painful hand is sufficient to discourage another similar move then no harm, no foul and you can set it aside but if it happens again or escalates it sure would be nice to demonstrate a pattern if it ever becomes a legal matter.
When you confirm his lie, you just gave him a witness and it sounds like you inadvertently gave him several people who can truthfully testify that he hurt his hand in an accident and look - this crazy bitch is claiming he got violent X years later solely to gain advantage in Court.
...sure would be nice to call a professional to the stand who could confirm what happened and your fear of telling the truth.
LexiCat - you are a pro on this topic - whatchya think?