Like a few others have said, you probably need a real separation. You're living in separate houses, but you're 5 minutes from each other and you're basically going at it every day. Honestly, what's the point of living separately if you're going to keep inviting that in?
It isn't doing you anything positive, nor your son. You want your AH to make better strides in his recovery and get to a point that he was at previously, but honestly it doesn't seem like you're fully committing to your own recovery. In another post, you mentioned you're going to al anon meetings but it's hard to commit to them because of your schedule. It may be time to re-evaluate your schedule, because you will have to commit to your own recovery if you plan on recovering from this.
I would suggest immediately trying to stop any communication or conversation with him that serves as a way of you trying to help him along with his recovery. It's one thing to be supportive, but it's another to make comments here and there to try to push him harder. And start being more honest with yourself about when these actions occur. It seems like you probably knew what reaction was coming when you mentioned what your son said to him.
The bottom line here is that you both need to recover, and your son needs a healthy environment. You can provide that by working on your recovery. You cannot control your husband's recovery. And it sounds like you are both better off working on your own respective recoveries without each other right now.