@Summerbreeze456 ugh I feel SO angry on your behalf. Your mum doesn't see you as an adult or an equal. Like mine, actively dislikes me.
I would stop giving her ammunition... Put her on a severe diet of any information about you and your family. Yourself and your children are your priority, and she is not even trying to be nice or supportive, so honestly I would reduce how much she's allowed to be in your life. You are allowed to do that,in fact, putting yourself and family first is the best thing to do..
Because how DARE she come and spoil your first precious days with your baby?! You'll never get those days back, and she's shitting on it all so badly that you've been forced to seek help online. Tell her to fuck off, lock the door, block her on your phone. She doesn't automatically have any right to make your life actively worse. Ignore her tantrums, remove yourself from her circus, protect your peace, and your healing (from birth and from her awful bullying!).
And then, when you feel stronger, put in more real measures to protect yourself. Move, if you truly want to. It's literally none of her business, in the real world ( not her controlling work of make believe,)Never see her, if that helps you feel better. We wouldn't tolerate all this from a friend or colleague, so our parents should be held up to the same level of basic respect, and she's falling very very far short of that.
I hope you find strength! Seeing mine trying to do all the shit things to my own kids helped me break the cycle. It's YOUR life, I hope it gets better.