He will only start slowing down on bringing new stuff into the house when he is a lot older and more infirm. How many years is that?
Even then he will find a way to order stuff online and his deliveries will stack up in the hall… unopened. Meanwhile, stuff will be piled up against the outside of the house, and around the perimeter of the garden, covered by tarpaulins that will eventually blow away, making the garden look like steptoe’s yard. He will become depressed with no way out.
It would take a whole new hundred life-times for him to go through the stuff and mend it and even then he would want to hang on to it, not sell it. It truly is an impossible task and there is no motivation to sort it, just to add to it.
It’s a massive problem when he dies. Somebody else has to sort it, get it all valued, sell it or, mostly simply dump it. It’s too much for one person to do. Again, an impossible task.
It’s such an expensive affliction too.
I have experience of this, indirectly. My friend would discreetly put one or two bits out for the garbage collection in the early days, but he would somehow know and bring it all back in again with even more stuff that other neighbours had put out. The hoarding behaviour really ramps up if it goes unchecked by a passive partner and neighbours become affected, causing arguments.
It’s impossible to live a normal life with a hoarder even if they do have other wonderful qualities.
Thirty years later my friend has built up the habit of staying out of her own house as much as possible, never looking forward to going home. She still loves him and makes excuses for him but has lost all hope that it will ever be fixed. She can hardly get into her garden to park her car and can hardly get through the front door. Danger lurks everywhere in the house. Everything gets lost very easily. He is no longer physically well enough to even contemplate doing anything about it but refuses to let anybody else throw anything as he knows it will come in useful one day. Sometimes he is right too - he might just have the perfect spare part if only he could find it. He sees it as saving money not spending.
It’s utterly impossible to talk him out of it OP or to make him see sense.
Do yourself a massive favour and stop banging your head against a brick wall because he will never ever seek help even if you threaten him. You are currently at the early stages of suffering from his illness. You need to act quickly before you suffer any more and go downhill with him.
Your one and only option is to live in separate homes.
Don’t discuss it with him. You are lucky in that it’s your home you live in, not his. So no more discussing, just tell him firmly and walk away. Refuse to discuss. Your mind is already made up.
Give yourself a deadline. Separate all finances.
Tell him your relationship with him is now over until he is back living in his own home for good. Tell him to make the plans to do that immediately or you will have no choice but to make him homeless.
He will ask why you are being so cruel. So then you tell him that one of you needs to stay well, balanced and reasonable for the sake of the children as they are more important than either of you. Don’t argue any more, walk away.
Stick to the deadline
Make him homeless if necessary. He will sofa surf.
He has had plenty of chances to conform, but he can’t, you have seen that.
You must now stonewall him.
It’s a very sad thing OP.
You have to bite the bullet and do it so that he can eventually visit and parent the children in a lovely, safe, uncluttered home environment without causing you any more grief.
Good luck !