"I’m not sure I’ve ever said abuse? This could well all be in my own mind".
No its not. Absolutely not. Giving their chosen target spaghetti head is par for the course in abusive relationships.
He has mental health issues.
Is that what he tells you or you think that he does?. There is no excuse or justification for such abuses towards you. Some men do use MH issues actually as an excuse or cover to abuse. He does this because he can and it works for him. What are his parents like Soldiers, they the same as he?. He learnt this from them most probably.
"He’s a grumpy miserable shit, but my fears could very well be an overactive imagination or my own hysteria".
Its neither.
"I’m not even sure he’s bright enough to play the mind games these abusers do".
He knows exactly what he is doing here, he has manipulated you into staying and or otherwise thinking that you would never manage on your own. Does he behave similarly around other people or employees?. No he does not. He chooses to abuse you instead.
I’m not an uneducated woman. I see the threads on here. Maybe I’ve read too many and am projecting.
Its nothing to do with being educated or otherwise, abuse happens across all creeds, monetary status and classes Many educated women as well can and do find themselves in abusive relationships for all sorts of reasons. Abusers can sniff out and detect vulnerability a mile off and exploit that in their chosen target to their own ends. You were targeted by this person. You are not projecting your own stuff onto him.