Well if you want to feel better about the situation, recent science has indicated that no matter how civil the marriage is, in almost all cases it is better for the child if the parents stay together. Apparently, even in healthy loving homes, having two homes, two sets of rules, two sets of family members, and changing where they live regularly has disastrous effects on a child's growth and development. So much that the recommendation is to try and stay together unless things like abuse and domestic violence are present (although even with these factors, the child is better prepared to deal with them when both parents are available). So you did absolutely the right thing for that girl, and it shows. It shows by her growth and the positive direction she's heading. You did good, not even just for what you could, you did good by all metrics.