Don't be too hasty to assume this is auditory hallucination - it could also be active imagination but poorly expressed. Keep an open mind. I could describe my childhood anxiety as my conscience telling me I would have a bad day, because for me EVERY day was a bad day. I walked to school each day with a sense of impending doom, which was usually justified. While I didn't specifically 'hear' voices, I DID mentally 'read' my thoughts in my head, and that could have been described as a voice. But they were MY thoughts, not something that felt imposed from outside. In my case, I put it down to an extremely vivid imagination coupled with detailed recall.
I hope I'm right, but I can understand your fear since you've been there before.
You didn't mention anything about your ex - can you talk to him about these things? Can you work together for your children, or is this one more stress for you?
I do hope you can get some help soon. One hope - getting help for her now, whatever the specific problem is, can only be to her advantage.
The cutting - that can be a separate thing, linked to her stress and feelings of being overwhelmed. Some kids tend to separate their emotions form their feelings and cut so they can feel the level of their pain - they are trying to link physical pain with their emotional pain. It is their coping strategy - not a healthy one, so they need help, but it is something they develop. My two middle children were cutters, neither of them is bipolar or similar. In their case it was just depression and anxiety.
She passed out twice in the last week: this could have also been linked to anxiety - hyperventilation (over-breathing) can do this. It's not serious, the blood gases sort themselves out while the person is unconscious. But it needs to be checked out in case it's something else.
Marg