A friend of mine who does family therapy is often heard to say “What is in the parents closet, ends up in the kid’s front yard”, i.e. whatever issues the parents think they’ve buried deep, become the primary narrative in the lives of the kids.
Food for thought. I’m sure you’ve unpacked (in counseling) your comment about how much the son is hurting your husband- because it’s likely a reflection of how much hurt the father has caused his son. Not intentional, not because he’s a bad person, not because he would EVER want his son to be in pain- but if your stepson was thrust into a situation where he was expected to be part of the Brady Bunch on weekends with siblings he doesn’t know (who don’t live with you guys… so the situation was doubly awkward) it was likely very confusing and painful for him.
Did he get one on one time with this dad during this period? Did he get to have his dad at school events and performances? Was dad the go-to guy who could give him space to grieve the end of his parents marriage? Were you on the scene before the marriage ended?
Hugs to you. This sounds challenging all around.