How to defang monster mother-in-law

Rather than allow her to create discord in your marriage, you should focus on removing her access to combustible material.

If discussing your baby's name always leads you down the same path, then stop discussing it. You just say, "Well, we haven't decided on a name; but we know what your preference is." If she wants to call your baby "Skipper," you can say, "You can call the baby anything you want to, though it might be awkward if that isn't her name." But you also need to be aware that this behavior might get worse after the baby is born.

Given that, the person who prescribed antidepressants to you should also refer you to counseling. I suggest you and your husband seriously discuss strategies for drawing and enforcing boundaries.