I'm not a hoarder, but I married one.
I had a step-dad who passed away, who was OCD, OCPD and also schizophrenic. I know what it is to live with someone who can't throw things away, although, at the time of growing up, I didn't realize that he was mentally ill...i just thought he was a bit eccentric.
When my mother divorced him, she carted 60 bags of junk out to the curb! When I flew home to NY, my family and I cleaned up 8 garages packed to the roof with everything...old kleenex, dirty baby diapers, wrappers and boxes from everything he ate, used, lived with! Since I was married and hadn't seen the extent of his illness till he passed away, I was shocked at what we all cleaned out of his apartment and storage garages! He even had steel-rigged locks on some of them, so that if anyone tried to take his stuff, the door would slam shut on them, most likely killing or maiming them. ( did I mention he was paranoid too?)
I don't save things I don't use or need. I find myself doing a regular inventory of books and clothes, and I have always had a motto: "out with the old, in with the new." My daughters tell me that to this day, they still remember me saying that and they live by it! (even my daughter with N traits!)
There is help for hoarders. Talk to your therapist about it, get to the root causes and learn new behaviors.
~Laura