Advice on an abusive relationship please

Advice on an abusive relationship please

Hi mum’s and wives/partners,
Sorry for the long post, but I’m hoping someone can please give me some advice on what to do in regards to knowing about a family member who is in an abusive relationship. My sister in law has confided in me and speaks to me all the time about how my brother in law verbally (and sometimes a push and shove here and there) abuses her, the things he says to her and the names he calls her are disgusting and worst of all, he does it in front of their 3yr old daughter. My SIL is very quiet, timid and introverted, she apologises for everything all the time and unfortunately he has destroyed all her confidence and self esteem, she has no friends and never goes out or anywhere on her own. She has told me how she just keeps quiet and does everything because she’s to scared to say or do anything that will aggravate him and set him off. She also says things to me like “if I just stop moaning and try harder things will get better, if I don’t complain about anything he won’t get angry”. He has made her believe that she’s always at fault, his anger is because of her, he’s told her that no one else would ever want her and that there’s plenty of woman who would want him and be a better mother to their daughter, which is why she won’t leave, she’s scared he’ll push her out of their daughters life. She grew up with an abusive father and she’s admitted to me that’s she’s married her father. The list goes on...
I have no idea what to do, firstly I’m the complete opposite and so is my husband (it’s his brother), my husband would never utter a bad word to me and I would never put up with that, so I’m really struggling to understand why she won’t just walk out, but I do understand I’ve never been in that situation and don’t know how it feels and that he’s brainwashed her into believing she needs him more than anything. Secondly, she’s confided in me and begs me not to say anything as it’ll make it worse, but I feel like it’s a cry for help, I can’t just ignore it! If something happens to her or my niece I’ll never forgive myself as I knew about the situation. The hard part is they live overseas, if I lived there I’d pack her bags myself and move her and her daughter into our house, but we don’t. She has told my mother in law parts of how bad things are but my MIL is the type of person who thinks her eldest son is an angel and is so worried about the “white picked fence” and what people would think that she won’t even tell my father in law about the situation because he’s “very busy and stressed” and he can’t have more stress added to his life... Don’t even get me started on this... this angers me beyond words.
So I’m at a loss, do I tell someone or don’t I? I don’t want to enrage my brother in law and he takes it out on her, but at the same time I can’t ignore it, I think maybe if more people know about it the more secure she’ll feel and have the courage to leave. I’m thinking of calling my mother in law and letting her know that I know about the situation and that she better do something about it or else I will tell my father in law the truth about what’s going on. Is this a good idea or not? My husband and his brother have never been close, we are both furious and heartbroken about this situation and feel like we have to do something. Any advice would be greatly appreciated. Thank you x