Going crazy

Omg my mother in law is driving me insane! She tries to make every decision about my baby, and every time I tell her what OUR (fiancé and I) decisions & plans are, she literally waves her hands dismissively and says, “I am the grandmother and I say...” and then laughs. About EVERYTHING! She’s trying to name the baby-and has even asked his family get together one night to put it to a vote, her names versus ours and whatever names are voted best is what we have to name it 😐. She wants to be there IN THE ROOM during and both fiancé and I want NO ONE there but he and I and she just won’t listen to either of us. And it’s getting so bad that she and my sister in law have threatened to call CPS (and lie and bribe folks to lie with them) on me to get my child taken away because I said if they can’t at least LISTEN to us about OUR child, then I don’t want them anywhere near my child. I’ve talked to my fiancé about how I feel and he says they’re just joking because they’re so excited to be finally be involved with their grandchild/nephew-family drama 🙄-and won’t call CPS & will listen to our rules and decisions...but I’m not so sure. Am I seriously just overreacting? Or should I push the issue until I feel listened to and respected? **sorry for the long rant I just needed to vent a little.