I've been through this particular mill - and the kids' dad was a vexatious litigator who has had maybe 20 court cases in his time, although courts never seem to notice this, so take the dick seriously.
He was harassing me and the coppers advised me to take it to the Family Courts and establish residency, decide about contact etc, before he tried to abduct the kids. Sure enough, he put in a counterclaim (whatever it's called) trying to get residency himself, suddenly wanting to take my kids to live 200 miles away from everything they'd ever known, in his infested one bed flat.
I hated the way he was so obviously litigious (you think 18 pages is bad - this idiot could knock out 100 pages, no trouble), and yet the system took him as seriously as if he'd been sane.
One thing they did at an initial hearing, on clocking how nuts he was, was to appoint a psychiatrist who had to evaluate him (and us, as well). erdict was that he was mentally ill and I wasn't. This was the biggest factor leading up to him (after 18 months) being denied residency and, on top of that, not even allowed direct contact.
One of the earliest warning flags at a very early on hearing (and there were countless hearings before the big day) was the fact he wrote these lengthy rambles.
Use it to suggest he needs a psychiatric evaluation. And hope the doctor sees it your way.