fairy he'll find it hard to move on, because as harsh as it sounds people like you are hard to find, someone who will overlook the bad, and continually look for the best in people.
My BF when I was in my late teens used to hit me, I swore it was my fault for upsetting him, not being the perfect GF he wanted. I never told anyone until omg after I had left him, part of me even viewed his behaviour as normal, I knew parents argued, I just assumed this was an extension of that. Everyone from the outside saw us as the perfect couple, and to this day there are still people who believe that I made it all up.
After him I met my (now ex) H, I used to tell myself he was so much better than my BF, as he never raised his hands, never left a single bruise. But he was argueably worse, he locked me in the house, took away the phones, even went as far as going into my work place (one day when he'd locked me in the house) and clearing my desk out and telling my boss I wasn't coming back.
I then had a very long period on my own, I felt awful, I kept questioning my sanity, feeling I must have done something worng as they were both so nice outwardly, and most of the time at the begining of the realationship. I even got so down I seriously considered taking my life. I got heavily involved in drugs and basically gave up on life.
Eventually I managed to drag myself out of the mess I was in - this was largely due to one fantastic friend and my mom.
I now know that I never deserved anything that those horrible men put me through, and they have not changed one bit.
This seems to be a bit of a me me me post, but I wanted to basically say, you're not alone, things will get bad, but they will really get so much better for both you and your DS.
Do not go back to this horrible man.
He's the one who has broken his vows not you
He's the one who will ruin your DS. It's his fault entirely if he's missing out on your DS growing up - what would you do if when he was older your Dh tried to hit you and your DS stood in the way and took the blow? How could you bring your DS up feeling that was normal?
All you have to do is look after yourself, and love your DS, there will always be people to support you if you go it on your own, please don't go back.