Thanks everyone. DS1 had a good birthday. The exam was ‘fine’ apparently. He’s got a couple more this week and will be finished on Friday. We had a lovely dinner out with his dad and stepmum. It was really good fun. 
Ex hid in his room when we came home last night - presumably to avoid having to behave like a normal human being with social skills and basic decency. I’m not sure who he thinks he’s fooling.
This morning he’s been a pain in the arse. The solicitor sent through the questionnaires about our house sale. He can’t find a box with bits of paperwork in it from when we bought it (this is apparently my fault). I haven’t touched it. I don’t know why he can’t just look in the online paperwork from when we bought it anyway. We’re using the same solicitors so they’ll probably have a copy of everything.
Then he started grilling me on questions about shit he’s paranoid about. He refused to discuss this in the living room and insisted I came upstairs and stood in his bedroom instead. 
As usual, he offered no suggestions about what he wanted to do, preferring to present it as my problem to solve. Then he got annoyed when I suggested he just answer truthfully that there has been a flood assessment (as part of the conveyancing when we bought it), we’ve had electrical work done since 2005 (we put in a new kitchen; obviously we had electrical work done!), and other things I see no reason to lie or dissemble about. We have the paperwork. It’s not bloody difficult!
Turns out that he hasn’t supplied his identity documents either. I did mine several weeks ago, quietly and with no fuss. You’d think it was a mammoth task from how he’s going on about it. He kept huffing and puffing about things and saying, ‘if you want to buy a house, then...’ over it all.
Shame your ex hasn’t made himself horribly ill @shitwithsugaron. I laughed at the 10% starting point your solicitor suggested. That’s probably a good place to start to get him to readjust his expectations.