Son calling another man Dad

My son is 6 years old. My ex has made things very hard for me since she and I divorced, and has done everything in her power to keep him from me, and make it very difficult to see him.

When my son was 2 my job relocated me from NY (where my son & ex live) to PA (where I still reside) I took the job to better myself. For the first 1&1/2 years I traveled to NY every other weekend, and spent the entire weekend with my son. I kept in contact etc. I have never missed one payment on child support so no one can even say I am deadbeat.
A few months ago, my EX became pregnant after knowing a man for 1 month. After that 1 month, they all moved into a new apartment together, my son started kindergarten, then they got married, and now he has a new brother. My son is having serious issues at school, uncontrollable crying, the class has to be stopped etc. He is now seeing a psychologist which whom I have spoken to in order to help her better understand where I may feel his problems are stemming from.
The main reason I am writing here is this. My son calls this man DAD & Daddy. I have had a few conversations with him explaining that I am his dad, and this man is just Justin. I had my ex get on the phone and nicely explained that I did not appreciate this, and that quite frankly I am not DEAD. She went on to say that "he likes to call him that" and said that he can do what ever makes him comfortable. The problem I have is she seems to be encouraging this instead of trying to correct it. I grew up with a stepfather who has been in my life since I was 5, to this day I still just call him by his name. When I am on the phone speaking with my son, he will keep saying "Hey dad" or "dad I need a bandaid" for example, so he is constantly speaking to this man and calling him dad while we are on the phone together. Not only does this upset me deeply, but concerns me that my son is confused and hurting.

[Kevin Kennedy, Ph.D.]

By focusing on this issue you are only exacerbating the problem. The important issue is your relationship with your son, not what he calls his stepfather. Many children refer to their stepparent by the names Mom or Dad - it doesn't matter. You would do well to re-focus your attention on the heart of the matter. You're letting yourself get distracted by this issue and it is not a matter that is worth the investment. You only put unnecessary pressure on your son by focusng on it.