My friend is trying to get back with her abusive ex, HELP!

Hello everyone I need a bit of advice! My best friend is trying to get back with her abusive ex. I don't know what to do anymore I know it is her life and ultimately her choice but I got a "murder/suicide" vibe from this guy the moment I met him and it was psychological abuse ever since. She has always been very secretive with me about the men she is seeing and usually will cut me out of her life when she starts seeing someone, which hurts. I learned from a mutual friend that she was fixated on getting back with this guy. I know there is nothing I can really do about that, I'm not trying to say "hey you can't do this or that" I want to show her that she is worth more than that so she can come to that conclusion on her own.

I've never been in a seriously fucked up mental/emotional/psychologically abusive relationship like that before and I just wanted to reach out to any of you strong wonderful women who would be willing to give any advice. I know that it's kind of out of my hands but I want to do everything I can.

Thank you!!