You are absolutely right to be concerned. You don’t deserve this treatment. Your son shouldn’t grow up watching this. He will think it’s the normal way to behave toward a woman he loves and will repeat the behavior. Your husband is very lucky that you are so understanding. My concern is that your “understanding” is helping him continue abusive behavior.
Being guilty isn’t solving the problem. Apologizing doesn’t make the hurt go away or make for a good model for your son. Sincerity after the fact doesn’t make up for his callousness during it. It’s time for him to do something about controlling his impulse to be mean to the person who loves him best.
I think your analysis is right. Often people who are bullied as children grow up to think there are only two roles in life: the bully or the victim. When your husband bullies, he feels strong. But then he is horrified that he made someone else feel as he once did when he was a target. So then he apologizes, but his inner self starts to feel vulnerable, like it did when he was a target. His only solution for that helpless feeling is to be a bully. So the cycle starts again. Your husband is still a “victim” in that he is echoing childhood issues.
The work of therapy in cases like this is to help people feel empowered without having to be a bully. Experienced therapists work with this issue all the time. Treatment does work.
I hope your husband loves you and his son enough to get himself into treatment. I hope he loves himself enough to really engage in therapy so he can be the man he could be. I hope you care enough for all three of you that you insist on him getting help now before he does more psychological damage to everyone, including himself.
I wish you well.