Good news about your DD 
I really think most reasonable and fair minded people would agree
As for your DP, I would have a private think about the big difference between what is “logical” (which I am sure your DP is very good at from his own point of view) and what is “reasonable” - which means taking other people’s point of view into account. And which your DH seems to find impossible.
he doesn't want to not be himself with people he loves. It is true that he also argues in this way with his mum, dad and brothers too.
And it doesn’t bother him that it upsets them. Or at least not enough to try not to do it. Because this is who is he is. And then there’s all this:
Then there was a whole nit picking argument about whether I had said 'it is of primary importance' or ..
I have had rants in the past about how he feels it is more important than anything (upsetting people and them feeling bullied) that people engage with the 'proper tactics of debate'
This latest one was entirely due to his anxiety
wishing he had the necessary tact to realise that starting this kind of fight (which he seems to use as a pressure valve for his own frustration at other ppl) is just really crap ATM.
it results in detailed analysis of stats and opinion polls and why they mean his opinion is the only right one to have.
he has been at the arse end of everyone's manipulations for a number of years due to being over trusting and easily manipulated
He's a maths person and very much likes to think the world is orderly and predictable.
His seems to be 'I like you, I trust you with my life'.
he moved out of his parents' house last year
he is a little socially awkward in that he always wants to engage people in some kind of debate about something or is a little overly interested in new people, doesn't always pick up on social cues that people would like to be left alone and not engaged in conversation 24/7.
He also struggles to imagine that the way he feels about things like birthdays/Christmas/mother's day (is not interested) is not how other ppl feel
he will not understand why I have pushed him out if I do and he will ramp up efforts to convince me
He did once say recently "I think I am an excellent BF"
When I am ill or struggling or down, any time there is anything serious where it is not exactly clear what can be done to help or I might need more intensive support he is uncommunicative and avoids me.
he let himself into my house while I was sleeping because he was desperate to explain that it was a misunderstanding
You know, all these points don’t sound like ADHD, not even unmanaged ADHD. But if you’d said he had an ASC then I would not have been in the least bit surprised. (Dual diagnosis if you like) People don’t seem to associate silliness with ASCs but it can be just another broken coping strategy. And yes I do know not all people with ASCs are like your DP, your DD may be very different.
I have not said this to make you feel sorry for him, nor because I think if he has an ASC it will make it any easier for you stay with him. I have said this because it could have implications for whether most of his distressing behaviour towards you is ever likely to change. ASC or ADHD, it is very deeply ingrained in his character and it’s doesn’t look as if the positive changes you said he’s made over the last year are changes in how he relates to you. He is good in some very practical ways and good company some of the time but his self-awareness and awareness of other people'sfeelings are not likely to improve much. He is not self-managing and you can’t do it for him. And if you do decide to leave you’ll have to be careful, his boundaries are all over the place.
I don't think I could trust him with an explanation of that's the route I choose.
Probably quite right. He’s unlikely to do anything with explanations but use them as a platform from which to argue back about why you are wrong to leave him.
I feel like Cassandra
That’s what they call it. Being Cassandra’d!
offred you are a fine person and you deserve a good supportive relationship. I’m not convinced this is the one for you any more. 