Don't test me granny

I had an interesting exchange with someone at Joseph's t-ball practice today. There is a lady that comes to watch her grand-daughter play sports every day. She also watches the girls little brother who's 2. Well, she doesn't watch him very well since most of the time he just wanders around the field picking up broken glass and drinking diet Mt Dew. Anyway, this lady is a real crab. So here's what went down:

Grandma, girl and boy are sitting in the dugout next to me watching the kids play. Boy takes a drink of water and spits it at the girl. Grandma says "Do that again and I'll smack you!" Boy does it again, grandma does nothing. Girl does it to boy and grandma again says nothing. Boy spits at girl again and grandma hits boy in the mouth. Hard. Boy stumbles back and cries. Grandma mutters "I don't know where he learns that stuff from". I think to myself "Uh, I think I might have an idea you stupid cow." I consider telling grandma that she's out of line but hold my tounge. Boy wanders around and cries for a little bit and then comes back and gets another drink. I can see that he's thinking about spitting again and grandma says "If you do it again I'll hit you harder this time." I jump in.
Me: "You can't hit him like that."
Grandma: (with a shocked look on her face) "What?!?"
Me: "If you hit him like that again I'll call the cops. It's against the law to hit a kid on the head or in the face like that."
Grandma: (to boy) "Ok, just do whatever you want then. I guess it doesn't matter if I let you run wild." (I was dying to point out to her that she had let girl spit without saying anything and that she always let boy run wild anyway but I held my tounge.)
After a short pause grandma says to me: "I guess you people don't think it's ok to tell your kids what to do. That's why kids think they can do whatever they want now."
Me: "Funny, I've never hit my kid in the mouth and he's never spit at anyone."
Grandma: "You people think you know how to raise kids?" (I'm not sure who she meant by "you people" here since I was the only other person in the dugout. Maybe she's been called on her mouth smacking before.)
Me: "It's not just me, it's the law. I could have called the cops the first time you did it but I'm telling you now that if I see you hit him again I will call."
Grandma: "Fine! We're leaving!" (She angrily collects boy, girl and their cans of diet pop and goes ..... to the other dugout.)

I did call CPS later and it turns out I was right. You cannot hit a child in the face or on the head like she hit her grandson. So. There you go. I'm not thinking I've stopped this crazy lady from every hitting her grandkid again maybe she won't be stupid enough to do it in front of me now. Anyway, it was an interesting day.