I am so sorry you are having to deal with this problem when you should be enjoying the last few days before your baby arrives. I would just treat it with the disdain it deserves i.e. don't mention the subject. It's your secret and yours to relish.
None of my daughters found out the sex of their babies and if they had, I wouldn't have wanted to know.
Good luck and enjoy your little girl when she arrives. If your Mum obviously favours her over the boys, then is the time to take her aside and give her the third degree
Baby Reindeer - anyone watched it?
Alphabetical girls and boys names January 2024