I think I'd be tempted to respond with
Thanks for your email, I'll be taking dd away on x day and I'm informing you as agreed.
As for your questions, I can see only one. 'can you please clarify that you consider it reasonable to diverge from the terms of the original agreement that we had?' A certain level of flexibility is required to co parent successfully, such as your request to swap weekends, my request to take dd away on x date, and yourself introducing gf on x before the agreed timescales. The changes made require flexibility on both sides.
As stated it appears we have both diverged from the terms of the original agreement. However if you'd like to stick to a more stringed agreement, I'll happily move back to the agreed alternative weekends, this way it will also avoid dd being in contact with your new gf.
Regards
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Then leave it as that. You don't have to respond to his previous email as it's not anything to do with him or your dc
As for his email.
Before I review your request can you please clarify that you consider it reasonable to diverge from the terms of the original agreement that we had? [...] This leaves me somewhat confused that you are deadset to stick to the terms of the agreement in certain areas, yet dismissive of other terms as and when it suits your particular desires
Nothing to do with your dc, he's trying to antagonise you - ignore
i have been very flexible to adapt to the fact that you work part time, a decision made as a family which you have used to your advantage in our separation, and left me to pick up the nursery bill for*
There's not a question - ignore
We are miles away from a 50:50 split, which should be the default position, and the fact that you are unable to accept this is absolute hypocrisy. It's strange that you are so passionate about sex discrimination and gender equality, yet you yourself are guilty of discriminating against me as a father and my rights to see my daughter
No question - ignore