You are the resident parent, you make the rules and tell him how it is.
It really does make me annoyed when I see comments like this.
Yes, there are some resident parents that abuse their children by using them as pawns in a dispute with the NRP but, generally speaking, you are wrong - the resident parent does not get to ''tell him how it is''
From what you have a written, this guy does appear to be a bit of an idiot but I sense that there is more to this than you are telling us.
Ex took me to court last year over child contact. It didn't exactly achieve anything different than what he already had so was pretty unsuccessful in my eyes. He however boasts constantly about how it 'sorted me out'
This sounds very much as though his view of the contact arrangements prior to the contact order is rather different to yours. Perhaps he was aggrieved by things that either he did not tell you about or you perhaps dismissed as being unimportant.
now feels entitled to makes demands on me. To give you an example, he took the order straight to the school and provided staff with a copy of it and said if they failed to send him duplicate letters regarding dd he could hold them in breach of the order
I would suggest that this isn't him being a psycho or making demands on you - this is an example where he is making demands on the school to include him in decision making regarding your dd. Actually, they are legally required to do this but it may be that the school were either failing or refusing to do so in the past. If he has got this far, it sounds like someone who has reached the end of their tether and has nowhere else to go.
It may well be the case that he - rightly or wrongly - partly blamed you for the school's attitude towards him.
You say that things started off quite civilly initially but have declined over the years. You portray him as being very irrational, and I'm sure that you are probably correct. However, I would suggest that this may well be driven by his perceptions of how you have treated him.
I have no idea if these perceptions are accurate or a total crock of sh** but, I would suggest, that this is what is driving him to act like this at the moment.