'OK I have re-read the whole thread, everyone is saying the opposite to what my DP, family and friends have said. Maybe I need to re-think the school change.
How do I cope with exH having shared residency, can someone tell me that? '
I am glad that you are taking people's comments on board. I think that is what is good about mumsnet-you get it as it is, your friends are not going to be able to be truthful because it would be too hurtful.
I don't think that redsocks advice is very helpful, she obviously has her own axe to grind. Your ex may not have been too good when she was small, but he seems well balanced now and he has a stable family set up. The courts have decided that joint residency is in the best interests of your DD. I think that you would be silly to try and use the schools situation to get her to live with you. Your DH will fight it and has a lot of good reasons-you have only the fact that you are her mother and want her full time. Even if you were to get the school change, if I was your ex I would refuse to be manipulated and would move heaven and earth to manage both schools.If you can't win there is no point in starting.
I do actually have every sympathy with you, I would hate it. However I didn't sound sympathetic because it is all about you. The part that I found was upsetting was that 2 little girls try and speak to you, and be friendly, and you don't want to know, I can imagine the atmosphere that you create. These little girls are innocent and you also said that their mother had nothing to do with the split.
I think you cope with it by being accepting the overtures of friendship. You make it easy for your DD by giving one extended family, rather than warring factions. (I have DCs from 2 fathers-each family treats the DCs who aren't related equally-it has never occurred to them not to). I would get to know your DDs sisters (starting by acknowledging that they have an important relationship with her)and you take all 3 girls out sometimes, or have them over to tea.
You have to see that your needs are different from your DDs. I think you would love it if XH and his family emigrated and just sent birthday and Christmas presents, your second choice would be weekend access, and your worst scenario is what you have. Unfortunately it is the exact opposite order for your DD. If you can't cope with it you should try the counselling, but it is important that you put DD first.
If you don't you may well find you are like YorkshireRose's friend (I apologise if I have the wrong person) and your DD will hate the bitterness and want to go and live with her father in her teens. In contrast you could be part of an extended family and get invited to DDs step sisters wedding etc in years to come. I know which I would prefer.
Life very often turns out to be not what you want but you have to adapt and change and make the best of it.