K.P.
So this guy is just your fiance'? I say if you don't have kids of your own with him, get out. Tell him that you think it is more important that he focus on raising his child without the interruption of you in the picture. His child is having problems and he needs to be there for him instead of worrying about you being upset. Also, his child could be having problems BECAUSE you are there. Children don't really like it when their parents are divorced, and when a new girlfriend or boyfriend becomes a priority for the parent, the children feel threatened and act out for the attention they SHOULD be getting from the parent. IMO divorced parents should not date or remarry until their children are 18. They need to be focused on raising their children and not their love life. The best thing you can do for this child and his father is to bow out gracefully and get on with your life.