The thing that makes this type of abuse difficult to peg is that we think it’s one thing if it’s done to us vs being done in front of a child.
Abusive behavior is abusive behavior -it doesn’t matter who sees it.
I suggest reading the book When Men Batter Women, because it describes not only the various forms of abuse (yelling, hitting, threatening, isolation, silent treatment, etc.), but what goes on in the mind when an abuser threatens verbally, or -as someone else described- menacingly, and how the person on the other end of that behavior receives it, especially women.
We know that men are typically stronger and can inflict harm; when a man is menacing like that, we also know those behaviors more often than not will escalate.
And that is the exact message he is trying to send to you: “I will escalate my behavior until you confirm.”
You were right to leave; you were/are right to request he seek anger management.
I’m sorry you are experiencing this.
Sorry for the late response. You should do your best to be honest with her, but not in an emotionally charged way. If she feels that you're trying to turn them against each other, she'll get defensive. If you can, therapy for the both of you will be a good idea, or reading books that highlight the different kinds of abusers (John Gottman's book when men batter women might help her recognize his abusive tendencies.