If this really is a one-off, your husband will come home absolutely devastated by his OWN behaviour. I have lost it a handful of times with my children (athough not said anything as bad as that but say smacked them when they were small), and I have felt terrible, ashamed, and looked to my partner to help me manage my own emotions when they have wound me beyond my own tolerance.
BUT, if he comes home convinced he's in the right, I would be very worried. Your son was in the wrong, and yes, you need to sit together and work out what to do in this situation, and yes, children sometimes need to see that a parent will snap and that they are human too. But, this is beyond that, my guess is that he did physically hurt him (pushing around?) as well as threaten him in a way that would be very scary as well as possibly criminal.
Your son's behaviour wasn't great, but it won't be the first or last boundary he pushes as a teen. If that's what your husband does over calling you a name, what's he going to do if he gets expelled, or shop-lifts (I know lots of lovely people who did this as a teen) or tries cannabis?
If your husband says 'I can't believe I did that' and turns to you for help, I might just about be prepared to help him to behave differently (as it must never ever happen again like that). If he thinks it's a justifiable thing to do to an 11 year old, you have serious problems.