Hi @Missy
I'm sorry to hear that Christmas time was hard for you. You are sound like a very patient and understanding person.
The question you raise, 'is it something that he can change?' Is a big question. It's hard to find answers for that. No one can be certain of how someone will behave in the future. What I do understand, however, is that for someone to change, they need to first acknowledge that's there's an issue, and then have the motivation to change it. From what you've written, it seems that at the moment, your husband is fairly closed off to making changes. No one can really know if and when he'll be ready to change, but you can start looking at ways you can make some changes to improve the situation. Seeking support (as you have done by posting on here) can be helpful. There's a few angencies that provide support to carers such as ARAFMI. Also Relationship Australia can provide counselling for issues within relationships
Also, you might find this dicussion, 'what if they don't want help' helpful. In this discussion, members, @Cazzie @GivingMick about some of the difficulties they have had with their partner not wanting help. I wonder if they could offer their perspectives?
@mountain who wrote this post may have some insights to provide. While her partner does not have an issue with hoarding, she shares some similarities with you in that her partner would not make changes, so she started to set boundaries and make changes for herself. @mountain any words of advice for @Missy.
I wonder if @Dax_dog is about to provide some advice.