OP I would also suggest some reflection on your part here too, if i am honest.
I am in no way excusing his behaviour, but generally speaking, I find that it is rare that relationship difficulties are due to one being 100% right and the other being 100% wrong. And, should you genuinely want to work on improving things I think you might have to be open to that prospect.
Playing devil’s advocate, was your DH a good partner before you had DS? Did he do his fair share of the household chores and admin, was he supportive of you etc?
If he was, I think that is worth considering/exploring why that has changed. In my experience, people rarely do a 180 change in attitude and behaviour for no reason at all. If he has, then I think that points to something going on for him personally or within your relationship- to be clear, I am not excusing his behaviour at all, but there may be a reason beyond “he’s just not a caring partner”. And that may help you to understand and eventually move past what has happened. if it is due to an issue between them, it may also point to a way to fix the issues they have.
If he has never taken on his share of the work or been a supportive partner, I am left wondering why you would expect him to change? You have set yourself, and your relationship, up for failure by choosing to marrying and having a child with a man whose attitude and behaviour you find unacceptable. Or perhaps you knew the relationship was not what you needed but hoped he would change? If so, that is also a recipe for disaster. I am not excusing his behaviour, but if you knew this was an issue, I think you have to take your share of the “blame” for the situation you are facing.
I have a good friend who is quite strident and a stong character, who definitely likes things “just so” and to be in control. There are reasons for it, and she is lovely- I am not criticising her for these traits. They have made her very successful in her career, if nothing else, and they are part of who she is. Anyway, she married a man who is much more laid back and is largely happy to cede a degree of control/go along with her needs. He’s not a saint for doing this, I suspect the situation suits him too. They have had some issues more recently where she feels she carries too much of the load, especially when it comes to decision making/logistics and carrying out certain tasks. But, at the same time, complains bitterly when he does things but not in the way she would prefer (even if outcome is fine/reasonable/the same as doing it her way would have achieved). When he occasionally does put his foot down and insist on something, she almost invariably absolutely hates it (with a few notable exceptions). When they had their first DC, she was very much “my way is the only way” and very much took charge- pretty much as you would expect given her character and past behaviour - but she was also quite anxious in a lot of ways and overwhelmed herself trying to be “perfect”. She often felt her DH was not stepping up to help her enough or in the way she wanted/needed (e.g. needing prompted when she wanted him just to do things) and I would agree he could have done more when she was finding things so hard.
However, he was also behaving exactly as he always had, and she was behaving as she always had. And, his experience of her is that she does not like or appreciate it when he does things without her input/on his own initiative/in a way she does not approve of- so I think he became a bit paralysed in not wanting to do anything for fear of upsetting her/getting it wrong at a time when she felt he should have been able to just get on with things. Additionally, she had (unintentionally and unwittingly) totally undermined his confidence in being a dad by constantly criticising and nit-picking (in my view borne of being anxious about wanting to get things right/her need to be more in control). He should have addressed this, and didn’t. My friend only saw her side of things, and was very resistant to the idea that she was contributing to their problems when we discussed it. However, when their marriage very nearly fell apart and they went counselling she was able to see that she was also part of the issue and that their relationship dynamic had not really changed, but the situation had and so they needed to make changes if they wanted it to work. Her DH also had to acknowledge his role in their problems. They have both worked on matters and I think they are both better off for it.
This might in no way apply to you and your relationship but I guess I’m wondering if the problems in your relationship are just an extension of your longstanding dynamic or whether there has been a sudden change. This might help you decide what to do. Nonetheless, i think you have to decide to whether there is something worth salvaging- and if so work on it with your DH- or not. And if not, then for everyone’s sake then you need to end your marriage and try to be effective co-parents.