Am I in my feelings to much?

So my SO still has contact with his ex. Even though now she's supposedly gay. She has a daughter that is not my SO. But they were close & he's the only father figure she knows. She's 6yrs old. She still calls well only  around Christmas time or when she wants something. I have told him that he needs to cut that communication off especially knowing the fact that we're having our family of our own & if he truly loves me like he says he does. 
Yesterday I saw his ex texted him on New Years saying Happy New Years. He swears up & down he doesn't want her or attracted to her in any way.  I'm not trying to sound selfish or mean or a bitch. But I feel like he's mine & im stingy & I will not share. 
Am I in my feelings for no reason?