As bad as it was, it's good you made the move to talk to the lawyer. My GD was five when her mother had an A, divorced my S, and immediately moved the OM in with her and the kids. The first six months were really hard for that little girl, b/c of how things were handled. After the first year, she was able to deal with the situation a little better. I'll tell you what broke my heart, was the day she told me that nobody would talk to her about it. She wanted her questions answered, and nobody would give them to her. She said she felt everyone just pushed her aside. So, my advice is to get someone qualified to talk to your little girl. Sometimes the family members are hurting so badly and are too close to the problem and just don't know how to help the little ones cope.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!