She's sees this type of attitude as normal behavior .. and as much as it may kill you there isn't much you can do, I would suggest calling a hotline or helpline for this kind of thing and talk to them about her problem are if they could offer you some professional advice because you won't be able to help her alone, I wish you and your friend the best of luck. You are a very good friend which is really hard to find now a days just be careful around the Guy.. you don't want to accidentally take a hit of any kind just because you were there.
In times like this, you just need to be there for her when she needs you. Usually people won't listen to what friends say at this point and nothing can convince them. But tell her that whenever she needs someone to talk to, a shoulder to cry on, you'll be there for her and mean it, do it.
The best thing is just support her a a friend, and I think you can stop with the advice and all sort that will only make the gap between both of you further apart, since you don't totally know her situation and why she's behaving like that. Sometimes, some people just need the time to let the cloud in their mind to clear, as for the mean time, just be there to cheer her up and be there whenever she needs you.