Worried how to split from my DH

[Playdoughy]

I think I am finally the stage where I want a divorce.
My dh has turned into this obnoxious prick that just keeps disturbing my peace and brings conflict in every day life.
He wakes up already nervous - it is either work or our DS waking up in the middle of the night causing him not to go back to sleep.
I am always the one that happily attends to our toddler and I go back to sleep.
He shouts at every little thing - loses temper with our little one (never hit him but shouts at him or plays cold/ignores him if he is annoyed by him - and this is what is a final straw for me).
He hates everyone, he turned away all our friends with rudeness and/or avoid meeting ups.
He is particularly rude towards weaker people (e.g. shop assistants, cleaning staff).
He is a type that always goes 1 meter ahead on the street no matter the pace you walk - I find it really difficult to ignore all of this anymore.
Why ignore I hear you ask.
Firstly he was nothing like this for years, this is something that he developed in the past say 5 years (we are together 10+). Secondly he can be his old self for 2 weeks just a lovely kind smart person and then turn into this prick without any warning for 2 days.
While at first these episodes were rare - like a day every 3 months, then a day a month, we have now arrived to a time where he is a horrible person to be around for most of the week.

He seeked professional help, showed some progress and then stopped going - back to bad patterns.

I am just tired and I don't want my ds looking at such relationship dynamics or being at the other end of his mental games.

What am I worried about is how complicated the separation gets.
We own a property together - split the mortgage bills, earn about the same.
He is petty, he won't agree to sell, he'd just stop paying I can already see - and I cannot cover alone.
He can be really cold and rude towards our ds but he'd fight to have his share of time with him and I'd be worried sick when he is alone with him as I know he doesn't even know what he eats and not to mention dh's temper and just closing himself in a room completely ignoring him.
I just feel it is easier for me to stick around for the ds. I really have no clue what to do, I am aware of the dv contacts and similar but I feel that's maybe an overkill...

Oh that sounds horrible OP. It sounds very stressful and you are right to want to protect your son.

First step is legal advice. This will help you understand what it will look like and what you need to do. It will also help you understand your rights, like what to do if he stops paying, and how to protect yourself.

They’ll also be able to advise re custody but I wouldn’t be surprised if he gave up on that quickly when reality set in. Sorry I can’t help more there, I’m in the UK.

Tempting as it is, I wouldn’t just tell him it’s over. He’s going to be difficult so you need to be well prepared and get as much knowledge and support inside as you can beforehand.

I’m sorry you are going through this - your son is lucky to have a lovely mum who wants to protect him

Not much advice to give here op but didn't want to read and run. It seems you have got your head screwed on and are doing the best for your child.

I know there will be lots of great advice given on here and I wish you all the best - away from this, as you perfectly put it, 'prick'.

I am so sorry about your situation @Playdoughy . The things you listed about him makes me think he clearly has issues, but just as importantly, is very immature. A mature, sane man would never treat a small toddler that way. To be fair, one thought you shared was way more than enough to describe the person he is: "He is particularly rude towards weaker people (e.g. shop assistants, cleaning staff)." - That is pitiful and one of the most disgusting ways a person can act. I do believe in showing who you truly are when you are dealing with people who have no power over you. He is objectively a terrible person, I don't need to know him in person to know this much of him.
Problem is, staying with a moron is never the way. It does not serve your DS, in any shape or form. I hear you regarding the worries around split time, but being anchored to this situation for good, every day, that is no solution. It will/could influence the type of person DS will grow up to be... I am not an expert of separations, but if there are reasonable concerns (and by the sound of it, oh boy, you do have those tenfold), I think there are ways around that in a legal sense, surely. Maybe document a few examples somehow? I am not too sure, but I urge you to look into what you could do on this front... How to prove it to fight you and DS's case. DS really shouldn't be around this sorry excuse of a grown man, and you, OP, deserve a loving and caring partner, not an overgrown manchild with anger issues (or being on your own in peace, if that is your preference, both are legit)