step mom problems

This is a lot.. my step mom is making my life SO stressful. My dad met her 2 years ago and I’m not sure what is wrong with her but I swear she is something else. Without going into much detail she is a huge hypochondriac, border lining Münchausen syndrome (but I’m no psychiatrist..) She is very demanding and pushy, doesn’t take no for an answer even if you say it 100 ways. She thinks she’s a doctor, she knows everything and has diagnosed my newborn as well as everyone else around her with everything under the sun. She keeps visiting which is fine but since baby was 2 days old she’s been asking to take baby over night. Every time we visit it’s a power struggle of her trying to force me to let my newborn stay with them. He’s a month old.. I am breast feeding... I’m not wrong to say no. It doesn’t matter how firm my boundaries are she still pushes, and my dad has to tell her to lay off and she still persists. I’m at my wits end, I’m not the type to sass people but I’m about to be very blunt with her. She’s also on pain medications that make it so she can’t drive... she thinks I will let her babysit when she can’t drive a vehicle? Heck no.