Monster In Law. we've all got one huh?

So little back story. My husband is 27, I'm 21. He has a 6 year old with his ex. Me and his baby's mom get a long great. We have no issues. My husband and his daughters mom had a lot of problems when his daughter was 9 months. They split and hubbys mom had to take care of her often because they worked. Anyways, I understand that's her first grandbaby but she already treats me and my unborn so unfair. This is our Rainbow baby. She wasn't happy when I got pregnant the first time and wasn't so happy this time either. She never talks about the baby and when she does she manages to bring his daughter into it. It's never about my baby, she just acts like there's no one on the planet besides her first granddaughter and it pisses me off because I don't want my child to be treated unfairly. Guess I just needed to vent and some advice on how to deal with it.