Child Abuse: Recording Issues

I was wondering how this works. I live in california. I returned home from a college class one night to my girlfriend to whom we have a five year old child together. Immediatley upon me entering our residence she begins to vent on a difficult night she had with our child. I had been attending a lecture and had a micro recorder in my jacket. I wasn't aware if she had been drinking or what but was aware she was acting strangly irrate. I pressed record on the recorder and she devulged to me that she beatten our child and left her cry herself to sleep for not cooperating with a homework assignment. (our child began kindergarten three days ago, the assigment being a coloring of upper and lower case letters, sadly.) I checked on our daughter and noticed severe bruising already forming, I didn't wake her. She also devulged how our daughter is my resposibility and not hers she can't handle her and she doesn't care if she passes in school, it's her(our daughters) problem and that my girlfriend was feeling suicidal. That night after my now ex-girlfriend had gone to sleep I took pictures and within that week obtained a restraining order for both her and I. My now ex is claiming myself to be violent to which is absolutly untrue. I was wondering how and if I will be able to use this recording.