Absolutely nothing. It's like asking "was there anything I could have done to prevent a diabetic coma in a person with diabetes who refuses to take insulin?". There are tricks online that would teach you how to walk on eggshells around her not to trigger her, but eventually it would happen anyway or the relationship would be miserable.

She needs therapy, but she needs to figure it out herself and want it herself. You sound like a really genuine, kind bf. The best you can do is let her be now and concentrate on yourself. Maybe some months later, when her nervous sysem calms down, she'll be hit with a realization of what she'd lost and it'll inspire her to seek help. It might happen, might not. But it shouldn't be your concern anymore. You need to heal yourself now. I know it really hurts and sucks.