Is discussion in person usually in front of dd? That can't work.
There is some value to face to face discussion, it maintains a relationship of sorts, is easier for mundane 'how things are with dd' stuff, it's harder to avoid answering a question and usually keeps things more measured - its far too easy to fire off angry e-mails and let things escalate remotely.
But, you need a record and he needs a way of recording dates so he can remember and stops 'forgetting and getting muddled'.
Really, insisting on written communication is the obvious way to go.
I'd be tempted in a way to discuss some things, for the reasons above, but make notes immediately and send a confirmatory email / letter, saying 'we discussed x y and z, points made were a, b and c, we agreed f' as you might with a work meeting.
Say 'I will consider this to be a true record of the meeting unless I hear from you by this date. Please raise any issues arising by the same date.' But this creates a lot of work and hassle for you.
You can even make notes while you're talking, again like a meeting. 'So, let me check I've got this right. You say the incident with the 18 certificate games was 'not a problem' and I am being 'a fussy cow' correct?
He might deny or 'forget' everything but, if you are relentless, you will have evidence of your discussions and he will not and will have no basis for disproving them. Witnesses or dictaphones could be handy! Do you ever talk in front of other adults?