He won't change. Abusers don't change. The only way it will get better is for you to leave, although I understand that's a scary thought.
His behaviour has got nothing to do with OCD. He is abusing you. Everything you describe is classic coercive control. Especially his reactions and threats when you have tried in the past to leave.
His behaviour is about having ownership and control over you. He doesn't care how you feel, he doesn't care that he's harming you - that is the whole point.
The FreedomProgramme (freedomprogramme.co.uk) would really help you wrap your head around how deliberate and incredibly abusive all of this is. (Including the fact he charms other people (how better to ensure they don't suspect what he's doing to you) and flips things around to say you made him behave that way, blaming OCD for his behaviour.)
My abuser didn't pretend to have OCD, but he still ticked off pretty much every single thing you have described.
Leaving will be hard, but you're more than capable. Your mental health struggles are most likely the result of his abuse. If you leave, they will be able to get better. If you stay, they will only get worse.
Thoughts for you. Do you want to spend the rest of your life like this? Because I guarantee it won't get better, only worse, with him.
Do you want your child growing up thinking this is how he should let other people treat him? Or how he should treat women?
Do you want him to be subjected to what you are? Do you want him to feel the way you do? This will have an impact on him.
Do you really want to be dealing with all of that on top of uni? Don't you want to give yourself the best chance possible to exceed and fulfil the dreams you describe in your first post?
Women's Aid can help you figure out to leave successfully and safely. Freedom can help you understand what has been going on and how to protect yourself and your son in the future.