Honestly this might just be me but if you've made your concerns for her (and about him) clear, then that's all you can do.. she's got to make her own decisions even if they aren't good ones.

The choice is now up to you, do you stick by her and wait out the potential for her to make the right choice? or give her some space for your own peace of mind and say she can reach out if/when things change for her. Either way works and you don't have to abandon her, but recognize she's gonna do whatever she wants either way, you can't control her she's gotta figure it out on her own. (Just my opinion please take with a grain of salt,, I don't know you guys! :') )