NWR: My momma's boy FI does it again!

My sister is having a baby and told me a funny story. Her MIL has insisted that her other grandchildren refer to her as “Mama Sarah”. This bothers my sister (understandably) and she would prefer if a different name was used… some derivative of grandma considering her MIL is not a “mama” to the child. So her husband finally spoke with his mother yesterday and layed down the law. I got home and figured I would discuss with FI (aka the biggest momma's boy alive) whether he would consider my feelings if I was having a child and his mother was demanding something that I did not agree with and that I was uncomfortable with. I said, 'if I am uncomfortable with something your mom is doing and she demands something she thinks is right, will you support me?' His response: Well it depends on who I think is right and many people do not like to consider themselves grandparents cause it makes them feel old. And I said, so if it was the same situation you wouldn’t have layed down the law? He was like, well it depends on who I think is right. This is extremely upsetting. One day I will have a child with him and it is frightening that he won't take a position on this. I feel like i will be 8 months pregnant and he will not consider my feelings and will only consider his mommy's. If it something that I feel is unappropriate as my husband he should stand by my side. I am really upset and concerned about this. He and his mom have gotten even closer because she lost her job. She plays victim, she calls him EVERY day and she is on the phone with him for an extensive period of time. He is so concerned and considerate of her feelings, but he could care less about mine. I really could use some time from him, I am very disgusted by this. His answer should have been very simple. “Lisa, if it something that bothers you that much, then of course I would speak with her.” He is really scaring me.