MIL issues.

My partner has a child with someone else, whenever we visit my MIL she always asks about the other child, never about how I'm feeling with her 2nd grandchild. She always puts pressure on us and asks us "are you sure you can afford this child?", we both have good jobs and can get by even if I don't go back to work after having my little one. My partner gets stressed every time we visit her, which results in us arguing. I don't want her to have anything to do with our unborn baby because she doesn't even act like she cares, does anyone else have this problem? Or maybe someone could give me some advice. At a dead end here, it's making my relationship hard and me thinking this baby is going to be 2nd best.