You need to have a frank conversation and tell him how you are impacted - that it is giving you the ick and killing the love (ie how it will have consequences and impact him).
You need to lay your cards on the table and ask him if he wants to be a man or a boy - if he wants to co-parent constructively with to build a solid, joyful, calm family life and home for his son and you both.
Then tell him where his current approach is headed.
You have to ask him directly if he wants to resolve the situation or not. If he gets defensive then you need to tell him that you can see that he doesn’t so there is only one exit strategy.
Some men have an unconscious hate for their own mothers whom they may have perceived as engulfing or overbearing - they have never reset that relationship dynamic but subconsciously punish the partner they end up with instead.
What was his childhood like - what is his relationship with his mother like.
Boundaries are all on you - they involve communicating them - with an expectation of a deadline but most importantly a consequence which is an action by you. It’s not about nagging. It’s about asking once maybe twice with clear deadline and consequence and then moving on.
If this doesn’t change and you stay it will erode you from the inside out. Your experience of motherhood and your DCs experience of you (even without overt words or behaviours) will be one of bitterness, resentment and contempt. Don’t do this to yourself and your DC. It’s a life of huge regrets. Ask me how I know.