Friend in huge trouble

I have a friend that has a very difficult life. A lot of crazy stuff happened when she was young (for example her dad tried to kill her, her mum was raped by her dad, her mum beats her up...) So a couple of months ago she left home and her dad is trying to find her.
Last night I had a chat with my friend on Facebook but I found out it wasn't her and it was her dad. This really scared me and I am really worried about her, I need to tell my friend that he is hacking her account but I don't want him to find out or say it to him directly and not to her.. I don't see her at all in "live" so I cant speak to her.
I don't know what to do, I stress, I'm always worried about her and I can't sleep.
I know this is hard to answer but please help!!

If you have her phone number or know where she is staying try to get in contact with her and explain the incident with her father very discreetly. Tell her then it would bes best if she changed her password, changed social networking sites or called the police as this a type of assault if he is terrorising her and just be as supportive as possible and if worst comes to worst tell her she can come and stay with you, if your parents will allow, or put her in contact with someone whom is able to put her up some where.
p.s make sure you aren't putting youself in any danger and if you believe you are tell your parents or guardians!!!!

I don't understand, "I don't see her at all in "live" so I cant speak to her" yet you can tell her to dump the chat window. If you can communicate with her securely in any way, tell her not to mention to him she knows what he's doing and to keep the existing account alive to feed him false information. If she closes the account it will only make him worse.

I wouldn't put much faith in any social networking sites to communicate securely under those circumstances. If he doesn't know where she is, using Yahoo mail or Gmail would be much more secure until she gets through this.