I don’t understand why he wants me to stay

I appreciate that your own experience is driving your view on this, but the only comment OP made that might be considered a sign of him having a problem is tha the doesn't care for himself. Everythign else is abusive. And whether or not that is due to mental health, if he's not willing to even consider that he's the problem, then no, she doesn't have to stick with him.

Let's list:
He doesn't contribute at home - lazy or abusive
If they break up, she must tell her son that SHE is breaking up the family - abusive and controlling
Threatens to withdraw care for child if they separate - abusive and controlling
Doesn't contribute financially (while also not contributing practically) - financially abusive. Also lazy.
Watches her through cameras - abusive and massive invasion of privacy. Also, controlling

I had depression for about a year and I didn’t even know what it was. It just hadn’t occurred to me because depression presents differently and I had different ideas about what it was the original posters. Husbands might be very paranoid about a break in, Hence, the cameras. There could be all kinds of reasons linked to his mental health as to why he behaves the way that he does. I know you’re right about mental health is not being an excuse for abuse and he should definitely be doing something about it, but it is a reason and not an excuse. And unless I have missed anything from what’s the original poster has described, it really doesn’t sound like abuse to me

Unplug or throw a towel on the cameras when you are there

but run he wants you to stay as life is easier and cheaper

you will have financial freedom even if your son has to go to wrap around care you want have a man child to feed etc and put a cms claim in asap

Run now see a lawyer go go go

Yes.....so unplug them.

OP, you haven’t told us enough about your circumstances. Where does he go when he’s watching you on the cameras? Does he work?

Who’s house it it? Rented? Social? Owned with a mortgage?

He’s abusive, without doubt. The answers to the above impact what you can do about it.

For a start, any health issue does NOT justify abuse.

Second, even if he IS unwell, if he's not doing anything about it, then she does not have to put up with it. I'm there supporting DH in any illness, including mental health, he might suffer. I'm gone the day he expects his illness to be something he doesn't have to acknowledge or deal with while expecting me to completely change my life to accomodate it.

I literally have no words. What planet are you on?

Or he could take responsibility for his own actions and let the OP leave without continuing to display what a dangerous arsehole he is

Unwell? No he sounds like an abusive controlling manipulative cocklodging wanker. Not sure that’s a recognised mental illness tbh

He's filming her without her consent because he's depressed, is he?

Jesus wept.

You committed to marrying him through sickness and health. He is mentally unwell, from what you describe possibly depressed. You should talk to him about that possibility, and ask him to make small changes until he becomes well again

Get him out of the house. If it's his house then get yourself and kid to your family's, or a mates.
You can tell your son the truth, that his dad does nothing and makes you really sad so we're not going to live together anymore.
He's an arsehole.

Absolutely this

This exactly - why would he want to separate when effectively he has domestic staff and a magic money tree ( i.e. you) at his beck and call

Leave. Now, today if you can. He's dangerous and I'm not saying that to be hysterical. His behaviour is escalating already and he's conditioning you to accept it.

So turn the cameras off when you're there and leave them on when you're not.

But really, you just need to get away from him as quickly as possible.

He doesn't get to decide whether you divorce him or not. And you should divorce him because he's an abusive cocklodger who doesn't love you and refuses to provide for your child.

Break the cameras.

First response is spot on.

Why has he put cameras around the house?

Pretty much. You haven't even said anything about him trying to make changes.

You carry on with your plans and leave him to figure himself out.

You've already noticed it's affecting your son's behaviour, so please give him the gift of a healthy atmosphere.

Oh and fuck that shit with the cameras.

Turn the fuckers off.

An adult reaction to you announcing you want to separate would be (after maybe an initial shocked period):

"I didn't realise things were this bad. Can we sit down and discuss this and see if we can find a way forward? I love you, I don't want to break up and I want to be a good father and I want us to be a team"

Or words to that effect.

You got:
"Waaaah! I'm not doing anything at all then. My revenge is to be shit dad. You're MEAN!"

Personally, I would feel secure and reassured that leaving was the right thing to do. And while it will be painful now, in the long run you will be happier and healthier.

Please contact Women's Aid. They can give you advice about leaving an abusive relationship. And get rid of his cameras. That is full-on controlling behaviour and is against the law.

He doesn't own you.
You have full autonomy over your life.

You don't have to convince him. This is a decision you get to make as a complete standalone. He does not contribute and he is invading your privacy. The trck is figuring out how you get rid of him - experience tells me that with men like this you can't get rid of him unless YOU leave. Do you have the finances to find somewhere else to rent?

YOu will also have to accept that he will most likely stop seeing your DS as a way to punish you. That's really awful but there is an argument that a man who can and would do this is not someone who would have been a good and reliable father long term so it's not like you're losing out there.

As for your son - he will tell him stuff. You will have to manage that. That will be difficult. But please, do NOT lie to him. Obviously, don't rant and rave about your ex but that doesn't mean you should take responsibility either.