sprite, when things were bad with DH, I thought about leaving too. And then we I worked out his 'diagnosis' which he agreed on.
That didn't stopped me feeling hurt. That didn't transform all the hard times into nice times. It just gave me a framework.
I felt sad to start with. Sad of what I had lost, grieving for the life I though I was going to have and now knew I would never have. it was a hard time.
And then I realized that these hard times were fewer and fewer because some the behaviours I could now see them for what they were, the symptoms of his 'problem'. So instead of feeling hurt, I could look at him and think 'Ah Ok this is just xxx. It doesn't mean he is mean/a twat/wants to hurt me (cross as appropriate)'
Having a diagnosis also gave us a framework to work from to improve things, change some of our behaviours to make it easier for both of us.
Now we have a nice life but not what I expected when I got married. It's a different normal, our normal and it's nice too.
I would really advise you to read as much as possible about dyspraxia and let a bit of time go before taking a decision.
I'm not saying you have to stay. Just that facing the fact that some his behaviours will never change because of his disability is a very hard thing to swallow.
Also remember that this guy will always be in your life in some ways as you have a baby together. Understanding dyspraxia is a must regardless of your decision.