My SO's mom wants to call ME a bitch and blame ME for ruining her relationship with her son when…

My SO's mom wants to call ME a bitch and blame ME for ruining her relationship with her son when look at what she did to him! Only because she was yelling at me with my son in my arms and he was trying to get her to stop, she hit him and they broke out into a fight! Wtf, of course I'm not going to bring your grandson around you anymore. You're way too unstable and I'm not going to let you hurt my family.