I know this is tough news to hear, especially from a child with mental health issues. But there are some good aspects to this, it seems. Her boyfriend wants to keep the child. This means he is committed. Even if they are not able to sustain a relationship, it sounds as if he will step up to the plate when it comes to caring for their child. Even though it’s not ideal, these can be two separate things.
Also, if she begins to feel really bad emotionally because of the hormones, she may decide to seek help on her own.
Is it possible for you to offer to take care of her during her pregnancy? Not all the time, but for stretches at a time?