How should I tell my grandmother?

I am pregnant with her first great grandchild. She is not a nice person, in fact she can sometimes be very rude...but, she’s family and she’s there when we need her. I know she won’t be happy for me. She has asked me before to stop taking meds to balance my hormones because I’ve gotten “so big and fat.” She wanted my parents to abort me when they announced to her. I need advice on how to tell her!! I don’t want to end up hurt.