I was assaulted by a manager
What is your reason for bringing this up to someone you have just met?
I've always felt the need to out my manager for doing this.
It's good that you are so honest, and I hope that you report this crime to the police as well.  Your manager was supposed to treat you and your coworkers with respect, yet he chose to cause harm instead.  This is criminal behavior, and he should be held accountable.
I'm not going to do that.
Not telling the police about what your manager did to you is incorrect because hitting a co-worker is very harmful to them physically and psychologically. This inconsiderate and dangerous should not go unpunished or you won't be able to live with yourself for not making it happen.