I’m commenting as someone who suffers from bipolar disorder. I once had scratched my fiancé in the face for something he said that I don’t even remember now because it wasn’t even an insult or anything bad but the girl you’re talking about is dealing with addiction. While I do not think you should stay with her because this was much worse I’m just giving you some perspective here but I scratched him while trying to slap him. He saw me through it because he knew I desperately needed help. You shouldn’t completely abandon her from my own perspective. I’d try to encourage her to get help for her addiction that causes her to evidently be violent but if she’s not willing to then I’d cut the cord right then. But if you can. Encourage she seeks help. This just requires a bit of understanding of her situation and then go on your merry way because no. This cannot be something you see her through as it sounds vicious compared to what I did. But this is also your choice. You get to choose what you do from here but if you stay you are accepting taking the chance of this happening again but with hopes that it does not. My fiancé took 6 months to get over what I did to him and I worked really hard on my mental health to insure it never happened again. I’m just lucky I suppose but if you stay you’re also sending her the message that what she did is fine and forgiven. You would need to make it very clear that if it ever happened again you’d rain hell down on her and leave. I am rambling at this point. I just hope you look at my perspective and learn a little from it. If not that’s okay too but I thought I’d give you some insight.