My parents separated when I was 12, my sisters were 9 and 7. At first it was awful, having to go to dad's on the weekend and feeling really disjointed for a long time. I never really got used to it. Once I turned 16 I was given the choice to not have to go to dad's for the weekend but I could go and visit whenever I wanted (which was a lot). I really got on with my dad and loved spending time with him but hated that all my weekends were taken up (typical 16 year old). Once that changed, things got a lot better and I relaxed a lot more in the situation. I started to understand a lot more about what happened too.
The things that I hated and that NEEDS to be avoided is talking about the other parent in a negative way or blaming the other parent for things. My parents did this a bit and it was horrible because both of them were telling me different things and I didn't know what to believe so I ended up zoning out when they talked to me about serious matters. Also, they gave me WAY too much information for a 12 year old about why things ended. I didn't need the nitty gritty. I just needed to know that things were going to be ok. This was the only seriously bad thing about mum and dad divorcing.
Another annoying thing was having to split christmas. It took the fun away because we always seemed to be rushing.....but now I look back and wish that I had to split christmas a million ways again.....my mum passed away five years ago. Small things like that seem so annoying at the time......
Anyway, my situation is slightly different to yours but just thought I'd offer it. You're daughter is lucky to have you as her mumma