Thank you for writing to me. I can hear that you are really worried about your friend because her ex-boyfriend has threatened to get his sister to beat her.
It sounds like you feel angry with this boy and that you want to help your friend, but I want you to know that it is not your responsibility to sort this out for her. I think that you have done the right thing by saying no when your friend asked you to speak to his sister. You can be a good and supportive friend without risking putting yourself in danger or getting in trouble.
This boy doesn’t have the right to make threats against your friend and by doing this he is breaking the law. Your friend might want to think about reporting him to the police. She could call the local non emergency number or go to a police station to speak to them about what’s happening. If your friend’s ex has made threats to her online or by text and she still has them then she could show these messages to the police. If she ever feels that she is in immediate danger then the quickest way to get help is to call 999.
You said you aren’t sure whether you should tell her parents about what’s happening. You didn’t mention in your letter what you think her parents would do, or how your friend might feel if you did this, so it is difficult to know whether that would be a good way to keep her safe. Maybe you could start by suggesting to your friend that she gets in touch with ChildLine. She can call us on 0800 1111, send an email or log on for a 1-2-1 chat, so the counsellors could support her and help her to think about her options. I know it can be really hard to be worried about a friend so please remember that the counsellors are there to support you too if you want to talk.