I hate asking this on here because I know there are a lot of weirdos that get off to it but I need help so I will not be explicit, I need advice?

My sister has developed a bad anger issue and she is being treated for it before she gets to big and it gets to far but basically right now she will just start hitting me or my mom out of nowhere and bite and pull our clothes. It isn't the worst because she isn't strong but she doesn't have any restraint and locks onto us and won't stop until she just calms down but basically a few days ago I was in her room trying to fix her television and she got frustrated that it was taking so long and she walked up beside me and swung her fist around and hit me right in the "bag" and obviously I reacted and was visibly showing lots of pain and she isn't stupid and I think she learned that she gets a reaction out of me when she hits me there so since then when she has her outbursts she deliberately tries to hit me there. I want to have kids of my own one day so I don't want to get hit there repeatedly and until she has this issue sorted out I don't want to constantly have to be guarding myself and usually I don't even notice her there before it's to late and she starts hitting.

Suggestions? My mom says just ignore her and don't react and she stops but obviously it doesn't affect her the same way and she usually just ignores her hitting and throwing tantrums because she can but I can't ignore that kind of pain
I hate asking this on here because I know there are a lot of weirdos that get off to it but I need help so I will not be explicit, I need advice?
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