Just one comment. Do you want your son growing up to believe the way your husband acts is the way he should act? I suggest that staying married causes more damage to your son than splitting would.
After reading other posts. I have a married couple friends whose relationship seems similar. Different issues but similar way of treating them. The husband is often verbally accusatory, treating his wife as if she were incompetent. He makes an accusation. She defends herself and the fight is on. I spent several days traveling with them and saw how her attempts to defend herself makes him even more anger. When she didn't respond, he escalated the fight. A no win for both.
I've had a similar relationship wit a relative. Took me a couple of years to learn that the fight didn't happen when I literally left the house. My marriage was is anot her example of when to leave. Dinner time had become difficult for me. I fixed dinner for my MIL, my mother, and the two kids. Then, I left to eat my dinner out. This, along with many other situations, helped me know I had to leave. I spent 3-4 years trying to make the marriage work. We had a couple of years marriage counseling. Nothing changed and I was beginning to feel trapped. Going out for my dinner helped me to feel more in control of me. We divorced.
When we defend ourself in reaction to accusations, the other person is apt to see that as proving our guilt. Our defense gives puts us in a one up, one down position of power. We are unintentionally telling the other person he has the right to accuse me; therefore I must convince him he's wrong. When we've done nothing wrong, we do not need to defend ourselves. We know we're in control of ourselves. We live up to our values. We are strong. When we defend ourself, we're saying he has control of us.