In retrospect, having had "other man" in my life after I divorced and seeing how it all played out with my two sons...I would do it again differently and not re-marry until my boys were grown. But you are already remarried. So..now just spending a lot of special time with your son will help. And I would wonder all of the issues regarding this dislike...your now husband is the adult here. Maybe some family counseling would help. I personally would not
put now husband before son and I would expect him to love my son. I think there are so many complexities in these situations is why I say in retrospect, I would just wait until children are grown to bring another person into our home. Good luck!