It is most definitely not OK. That is domestic violence. Just because you are a man and she is a woman doesn't mean it's OK.
^^^THIS. This is also a great opportunity for a very clear, very easy to set, very clearly defined consequences BOUNDARY. "I will not tolerate any physical violence of any sort, no matter how minor, against myself or our child. If you initiate any such, i will call the police."
Doesn't matter if she's a guy or a gal, she strikes you that's "battery", and threatening or motioning as if to do so is "assault". Both are crimes in every jurisdiction of the United States.
That's free legal advice, BTW, I usually charge for mine, lol...
H53/W51, R-ing 4/'18
"Do not arouse or awaken love until it so desires"-Sg.of Sg 2:7
"So oftentimes it happens,that we live our lives in chains, & we never even know we have the key"-Eagles III 1:3