SO's Mom

Jewel
I just want opinions.....so this past year I have been trying to build a mother daughter relationship with my SO's Mom and things were going pretty ok in the beginning. Then the arguing between her and my SO began because he was giving her less money than before(he changed jobs). She would say all kinds of mean thing about him and I but I would just brush it off and keep moving (especially since she would always try to be my friend afterwards). Well its been half a year and things are horrible. My SO won't give her anymore money because we need to move and save up for baby. Now she says the most vile things about us, blames everything wrong with her life on my SO, starts petty arguments and always screaming fuk us. We even found out she's been spreading lies about us. She seriously stresses me out and I want nothing to do with her anymore. I refuse to talk to her or even be around her. Am I wrong for not wanting to invite her to my babyshower nor let her come to the hospital after the baby is born? I just can't deal with her.