Relationship recovery quandary?

Your first obligation should be secure your child's safety. This is not an option. This is your responsibility and should be your top priority. As for helping your child's mother, only you know whether this is important to your happiness. Personally, I would want to help her if I were in your situation, but only if she is willing to seek treatment. If she does not willingly accept treatment for her issues, she could put your child in danger. Honestly, your questions are better suited for a professional. I recommend obtaining legal counsel and meeting with a psychologist who specializes in family issues involving abuse. You need to get your daughter into treatment ASAP, and a psychologist can help you understand how best to respond to your child's mother and what actions to take.