My ex has been with his gf for about a year or so and over the last few days our five year old has started calling her mom. Just once in a while but it's starting to get under my skin. I'M his mother, not her. She said she doesn't respond to him when he calls her that and my ex said that he has talked to him about it. When I asked ds about it, he said he only calls her mom when he misses me. Has anyone else go through this? I'm trying to just blow it off, not make a huge deal over it, but it does hurt. I have nicely told him she is Minnie (his nickname for her) and I am mom. That's when he says it's because he misses me when he's at daddy's sometimes. Grr.. I've lost my marriage to her, I will NOT lose my son too!