I agree with the others who state or imply that the issue is your ability to communicate your needs to your husband and his willingness to factor in your voice as an equal, in the decision making process over the house, and the family.
I do not think there is the same "right" thing to do in each case, or any case for that matter. I believe there are a range of solutions that may work or will never work but we have to be on the same page if we are subjected or expected to take responsibility for the results.
We have to have consent, which it, seems you have withdrawn or never given.
In Echo's case it is clear cut. Her younger children could never and did never consent that they were their sibling's victims.
Some of us have one child, or the others are grown, and our decisions impact only us. We are willing, for a time, to choose to endure, or not.
I would begin with the idea that you are in this relationship and household by a personal decision and you can leave it the same way. I would think about what you need to stay. And only then when you are clear, (maybe you will want to go to personal therapy), I would have the necessary conversations with your husband (with or without a therapist.)
We cannot force our mates (or anybody for that matter) to do any one thing they do not want to do. We can only decide what we want, to communicate it. Only if there is consent and motivation to work towards a goal by each person in a relationship, will there be the potential for unity, clarity, mutual respect and boundaries.
It sounds like your stepson may be opportunistically taking advantage of the lack of communication and unity--to operate.
By your deciding to declare your needs and boundaries, you will be helping everybody, especially him. In anything worth having, there is the risk of loss, too.