Jo, I have been there. I know what this is like. I can tell you that my experience proved to be a good one. I did have MANY nights where I wanted to run over to her father's house and take her back home. Most of the time it was because she would call me crying. Telling me she missed me. Telling me how awful her father was to her (not really true). Telling me they did not provide certain things for her (not true).
When I did move to her dad's town, difficult child was very happy to be with me more again. We did split 50/50 time with difficult child after that year. But, I could see such a difference in her.
I would give it a specific amount of time in your head. Maybe at the very least 3 months. Before you even entertain the idea of her coming back home.