While having a new boyfriend is exciting, as it usually is, you have another role that is much more important than any new person that comes into the scene. Your son. You obviously know that because you have made certain agreements with your ex to keep the relationship between the two of you civil and open so that your son can see that he has two loving parents that are going to take care of him, no matter what. And that's so important, even if you aren't together. This new man of yours needs to be more understanding and supportive if he wants to be a part of your life. He is the new person here, not the child, or the ex. And he shouldn't have a problem with the fact that you get along with your ex. If he does it's because of his own insecurities, and he needs to get over them. I can tell you from experience, it's better to have a good, civil relationship with your ex, than not. Its so much more unnecessary stress and drama that your child doesn't need to see, or be around. Good luck.