Should I speak up or mind my own business?

My brother has custody of 2 girls from his 1st marriage and he and his current wife have 1 girl together. While I'm all for being strict and setting rules for kids I think there is a fine line between being strict and just being mean. I think my sis-in-law has crossed that line. She is strict with all 3 girls, but I feel she is mean to the girls who aren't hers. The 7 y/o was sent to her room for time out whatever reason and then came back out to get something. My sis-in-law starts screaming at her and shoved her down which resulted in her knees being black and blue. I don't think my brother sees whats going on and I really think the girls are scared to say anything. I only found this out when the girls had a weekend visit with their mom and they told their G-ma and she told me. Their B-days are coming up and they always have a B-day party on the same day..they will be 8 & 12. I don't want to go because I want to kick her a**. Do I talk to my brother? her? Mind my own business??
i think you should talk to someone! brother probably best. a person that is abusive like that will only get worse! If your brother doesnt do anything about it then it is up to you to take action! protect the children! PLEASE!! People like that think they have power and will gain more and more power until something bad happens. then they run.
I think you should tell your brother what his girls said to their grandma because someone needs to check in on this. If all else fails call social services you can remain unknown. I know its hard but someone has to watch out for those girls and he might be too far up his wifes butt to see it.
THIS IS TABBO17 AND I JUST WANTED TO YOU THAT WHAT I ASKED IS NOT CRAZY WHEN SHE BY THE WAY, ONLY TAKES ABOUT 30MINS AND SHE IS STILL SO SLEEPY. IF YOU CAN'T ANSWER MY QUESTION WITHOUT BEING RUDE THEN DONT ANSWER IT. THANKS TABBO17
Yes, some women can not parent other ppl kids especially if they belong to the ex.Talk to your brother privately let him know you witness her shoving her,because that is abuse and it will cause the girls to be afraid to admit she is hateful.Also,she might be jeallous of the relationship he has with his ex and his other kids.TALK TO YOUR BROTHER!!
It's your moral responsibility to say or do something. You have information that the children may be experiencing physical abuse.

I can't see that it would do any good to talk to her or your brother. They, together, are the problem. The G-ma might be a possibility. Have you considered talking to the girls' mother?
I believe you should sit them both down, and discuss what the problem is I mean it is your business you are their aunt.If he won't listen then take matters into your own hands, for one they are not her biologically children so she really don't have the right to put her hands on them.


Answers:
*I would calmly discuss your concern with your brother and his new wife at the same time. Let them know that you don't want to cause problems because all 3 girls are your nieces no matter what. However from the stories the girls are telling, that you believe that she is close if not crossed the fine line. Just be honest!, Maybe get the Gma and other mother and your mother and the new wifes mother all together and maybe all of you together can confront HER or him.