The relationship that your sibling has with her boyfriend is (presumably) different to the relationship that she has with you. For instance, your sibling and her boyfriend are having sex - while you and she don't.
Your sibling has the right to make her own mistakes. She is an adult and you should respect her autonomy, choices, preferences, decisions, needs, and boundaries.
All you can do is point out to her the abusive behavior of her boyfriend, tell her what you think and feel about it, and offer your help should it be needed.
That is extremely hard. I'm going through something similar with my mom. You just be there for them as much as possible. Be as honest with them as you can. You don't have to be around him or be nice to him, but you shouldn't "down" him or be mean. That will only push her further away. When she needs you, be there. You call her, she probably won't call you as much or talk very long, but if you keep contact, you are doing your part and when she "comes back", she'll turn to you because you were there for her. He will try and keep her from her family and friends. It's easier to control and abuse her when there isn't outside influence to tell her to leave him. Just hang in there and do your best to support her, but try and get her out. It's very hard, but you have to be strong for her, she can't be strong right now.
Darwins theory of evolution
You make the best of it,AND try to get to know them.you might just love your new sibling in the end.i know I do!:)
Bubble bath and loads of chocolate! ;)
Pray for him and hope he is safe. If you can cope with it, so can he.
You don't cope. Don't think about it. It was before he met you, you couldn't prevent it.
drop him and start over with a n ew life its hard but you can do it
Let him have her, and find yourself someone who respects you.
You move on and say, still without you, life still goes on.
Having a conversation with your boyfriend and his bestfriend about what bothers you about his best friend may be a good way to cope.
If your boyfriend is depressed and you love him you should try to convince him to get help. He can see his doctor to talk about the depression and possibly get some medication to help him. It can be hard to cope when someone you love is depressed. Just be strong and be there for him and let him know that you care.
I am not postiive, but this is my responce: Cats used to be wild and when one died they knew "we can not sob, we must keep going on to survive: Its instink
It may feel like breaking up with a boyfriend or girlfriend when your best friend breaks up with you. It is best to surround yourself with supportive people to cope.