Mallika offered some great advice, I just want to add a couple of things. Often someone with abusive behavior, especially if they have mental health struggles, is at least somewhat codependent. Based on a couple of things you said I think that might be the case here. I want to stress that if this is going to work you're going to have to stop being codependent on one another. You need to have very, very firm boundaries with her.

Honestly I think you should go a short period of time with no contact or minimal communication in order to break that strong hold, but that's just me. I just know it can kind of be like a drug; you feel like you NEED your partner and nothing is okay without them. That cannot be the case or this won't work. You seem pretty stable on your end but this is something she has to understand, and even though you're solid you need to make sure she is too.

I want to say one more thing and I am debating how to say it, but I am going to try. I believe, based on personal experience, that the future of your relationship cannot be the only thing that motivates her to get better. The reason I'm hesitant to say this is because sometimes having an external goal or motivator does cause people to make great changes that do sometimes last. But relationships are not always stable, and maybe you don't want to hear it, but they do end. Even if this is your happily after ever and y'all stick to it, when tough times happen she might revert to old behavior patterns because the foundation isn't solid. She needs to be doing this, to some degree, for herself. That is the only way this will truly work out in the end. She has to want to change not just for y'all's sake, but for her own joy and stability.

She probably won't be perfect because new patterns of behavior take time and continuous repetition, but I hope that in six months y'all are able to come back together as healthier, stable people with a good, solid foundation for your relationship. Good luck.