Should I contact my son's father's wife and tell her how her husband has little interaction with his child?

I have a strong feeling that he goes around telling people that I keep our son from him, which is totally false. We we engaged and broke up when my son was 1 and he married this girl last year. I dont care what goes on with them and their kid but I just want to know why isnt he interacting with his 1st kid. He hasnt seen him in a year. My fiance is like the father figure to my son. I dont think its fair to him because my son is getting confused on who his father is. Should I contact his wife and tell her. I dont want any problems and not looking to argue but my son deserves his dad despite the fact he is acting this way right now