Does this woman see the child? Has she gotten any custody rights?
I was granted full custody and visitation was at my discretion. I told her to go back to Idaho and get counselling. When she could provide me with a therapist who could assure me that she was no longer a threat I would agree to visitation and I even left it open to trying again with our relationship once she had received treatment. I didn't hear from her for about 15 years. When I did hear from her I still had that door open but she never took advantage of it.
During that time I made no secret of her existence to my daughter and what I told my daughter was that her natural mother loved her but she was too young and was not ready for the responsibilities involved in being a parent and a "wife" (we weren't married but that was her role). I told my daughter that her mother really struggled to deal with all the changes in her life that happened so quickly and so she went back to Idaho.
When my daughter was 17 I contacted her mother and asked if she was ever going to make any effort. She said she would like to so we opened up a dialogue that lasted for about 6 months. She came to Oregon to meet her daughter and they spent a weekend together and Trinity and I welcomed her into our home. She really tried to be my daughter's mother figure, but my daughter was raised by my ex-wife (Jennifer) and Trinity so my daughter just wanted to be friends with her. She did not take kindly to that and insisted that my daughter think of her as "Mom". My daughter refused and she went away again. They text each other on holidays now and that's about it.