I am great at decluttering/organizing my stuff and my kids stuff. DH's stuff is everywhere and he either never puts stuff away or puts stuff in random places like a hammer in the cereal cabinet. Nor does he respond to requests to take care of these issues. (He's almost a hoarder. I think if he had access to more than $750/month he would have a house like on Hoarders.)
So I put his stuff in a box and when the box is filled in goes in the garage. This was advice per our counselor. Now the garage is stuffed. Not ALL of it is his but 99% is. I don't have the mental or physical energy to deal with this nor the time. He doesn't work and I work full time with two bad discs in my back and fibro too. Any advice on dealing with an almost hoarder.
Rent a truck or dumpster for a month from now. Book 2 days off work. Tell DH what is up - that a truck is coming one month from now - he needs to go through his stuff and decide what to keep because (agree on a reasonable amount) you do not know what is important to him. If he wants help, offer, if not - leave him to it. When the truck comes load up anything not looked through, or anything has decided he wants to throw out. Donate used stuff if you are up for it, but the most important thing is to get rid of the stuff. If donating becomes too much of a chore, do not do it.
Waiting for him to do it will get you nowhere. You and the kids have the right to a livable house.
I do think there is a time to work on gently prioritising things, and work on things such as "one in, one out" but those are after a big purge has been done.
I have also pm 'ed you a book title.