He sounds passive agressive, just refuse to play his game. He is getting something out of his behavior, whether its feeling like a marytr or what, he goes this for a reason.
Personally, I would sit down with my husband decide what the criteria your willing to accept from this step son. Lets say you decided that you are not willing to continue until he sits down and has an honest open conversation about what was and still might be troubling him. If you think it might help, involve a family therapist. Tell him, these are your terms, they are not negotiable period. Let him know the reason, you need to have peace and stability in your family and if he is going to be part of the family then this has to be dealt with.
I can't stand people who are controlling and manipulative, just don't play their game. What they want is to be able to treat you like [censored] and there be no reprecussions for it. Thats not the real world.