D.S.
People don't change that much. And keeping an abusive man in your life may actually be bad for the child. Do you want that to be your child's example of how to behave? Your child may grow up and behave exactly the same way because he will learn from watching his father. I think you should separate, and deal with the fallout of that. Otherwise you will just struggle through however many years of the same behavior, your child will be exposed to that, and then the separation will happen, and that will likely be even harder on the child. That's my opinion.