I can understand your frustration - it's not easy when we see people we care about hurting.
Please continue to resist the temptation to rush in and tell her bluntly that her misery is largely self imposed! (I'm guessing from your post that you haven't done this yet). As you say, she isn't very receptive at the moment and the difference in your ages means that you are very much her baby brother so she is unlikely to listen to you!
I also think that you will need to let go of your need to change her. Yes she is hurting and upset, but she will only change when she is ready. You can guide her gently to your world view, but you cannot impose it on her.
So first off, start with yourself. What is it about her actions that upsets you so much. How will you deal with that part of you that is annoyed with her for not seeing what is so obvious to you? How can you love her and accept her
just as she is now without judging her? What can you do to support her and show her you care for her without trying to change her?
Then sit down and
listen to her. Not with a view to impose your own solutions, but really listen to how she feels and thinks. She may need to really talk through some of her feelings to release them. It may be that she creates dramas in her life so she has some attention, so give her postive attention by listening to her and valuing her and ignore all the dramas. (I appreciate this isn't easy)
try this article for info
Over time you can gently drip feed your ideas such as telling stories about how you used to think and how you have changed. She may reject those ideas initially, but if you live them and embody them fully you are then giving her a postive role model for change.
I'm new to using the LoA, but you might visualise a healthy happy life for her and send loving thoughts her way.