What would you do? (Condensed version below)

Shortest version I can muster: My mother is super abusive - has been since I was a child. She is rude to my husband and spreads lies about us to the entire family. She blocks and “disowns” me frequently, and tells me “she only has to love me because I am her daughter, but she doesn’t like me.” I have severe anxiety, PTSD, and depression due to her years of mental, verbal, and sometimes physical abuse. She is bipolar and will flip on a dime - when she first meets people she is so sweet and then she literally turns into a conniving, manipulative nightmare. After almost 2 years trying to conceive - I am pregnant. Everyone knows but her - my close friends, and my in-laws. I feel like I cannot tell her. For example: when I told her our first IVF failed, her exact words were “well you shouldn’t be trying to have kids anyway.” I’ve been married two years and we both have full-time jobs. A few years ago I wanted to kill myself and ended up in the hospital (long road but I am okay now :)) and her exact words to me when I told her after the fact were “you trying to kill yourself is on you.” No support at all - only fake love when I decide to subject myself to her torture and go home to visit. She threatened to call the cops on me, and accused me of stealing the last time I visited. I ran out of the house and almost crashed driving home because I was crying so hard.

So there is a short version. It’s hard because I still have this attachment to her and long for her love, even though it can’t happen. So please help me guys. Should I tell her now, later (after baby is born), or let her just figure it out and not say anything?? I am having a really hard time with this. My husband and I’m-laws agree she will never be alone with my child...