MIL and her wishes

My MIL is pretty much curios person. And wants to put her nose in someone else's stuff. And doesn't know her limits. Everytime I put the line, it ends up with a fight. I can't stand it anymore! 😩 The last thing is that I dont want to know the gender. But it's not important what I want. She wants to know and that's what is important. My husband knows the gender. We agreed that he is not telling anyone. But she calls almost everyday to find out. I know that my husband will eventually crash in the end and will tell her,because she's so stubborn. And I hate it. She doesn't respect anything. I really don't know how to manage with her anymore. Help!