@Onetwothree45 You are back to viewing things in terms of 'stuff' rather than recognizing that 'stuff' is just the symptom of a MH disorder.
I'm hoping others here might be able to take this post and explain emotional transference more concisely than me.
hoarding - noun (KEEPING)
the act of collecting large amounts of something and keeping it for yourself, often in a secret place.
Repeating myself but again: there are people like Barley Sugars Dp who bring in and don't throw out and are considered to be hoarding who barely notice removal of stuff. That's because they are hoarding stuff but don't have hoarding disorder = suffering significant serious emotional distress when attempting to throw stuff out, or it being thrown out. It's this that causes your partner to lash out (and others to lash inwards dangerously) whereas Barley Sugars Dp barely notices. It's the difference between bad habits and a MH disorder.
There are hoarders who don't actively acquire. They just keep what comes in naturally. Most of them have no issue with walking away from the lot, or it being cleared out, but among them are those with hoarding disorder for whom it's an emotional displacement and who can't just let go.
Hoarding disorder isn't defined by the amount of stuff, the type of stuff, or the amount of available storage. It's defined by acquisition and far more importantly, the acute internal distress suffered when needing to dispose.
Are you making his reactions when made to choose seem worse ? That unreasonableness rightly worries you. You can't generally have meaningful discussions that result in agreed outcomes, unless the outcome is him keeping.
The shed and garage will fill, during which time you will be battling over stuff that he doesn't want stored externally, and the gradual encroachment of materials that can be stored in the garden, to make space in the outbuildings. The children will be expected to maintain their own safety by not being near it.
Slowly and quietly everyone will come to understand that his stuff represents him, the very damaged dysfunctional part of him, that he puts to one side in stuff (everywhere) in order to function as a nice person/partner/dad/worker, rather than carry an unbearable load around daily. We don't know we're doing it, and it takes a long time to get your head round.
It's why the forced clear outs don't work, it's why making yourself dispose feels like throwing yourself away. It's why recidivism. It's why stuff is just symptom.
Transferring huge unmet needs and pain and emotion onto stuff allows us to function instead of be drowned by what's internally wrong. Others develop different MH conditions around what's internally wrong that bring attention quicker. We're often the ones determined we're OK. Eventually however, we drown in the stuff instead.
Hoarders without realizing, use transference on to stuff to fill and bury an emotional chasm. But it is never full and eventually the sheer amount of stuff forces the person (often via others) to beg to know what the hell is wrong with me? or to decide everyone else is the problem and become reclusive.
It's not just drowning in the stuff that that you should fear for you and your children, it's that living with his reactions to disposal of it, are what you are planning as a normal future for them and you.
He needs serious amounts of help in order to function normally as a person, but you're seeking to enable his dysfunction, so he can help you, in the state he's in.
I don't blame you, I understand whats happened, I can feel your turmoil, and it's all really sad. I'm just trying to get you to see exactly what the situation is.