I watched The Hoarder Next Door last night; it made me think really hard about what the items I cannot seem to declutter represent to me. For example I home ed one child and I have lots of Art books. He is 14 now and not that interested in art, well not for quantity of books I have bought on the offchance from various charity shops. The Art books represent my desire for Him to do Art. In reality the tidier bookshelves and calmer environment that getting rid of those particular excess books or at least some of them, is a pay off from losing out on the actual books. I have to come to terms with the sad fact that he doesn't like art much. There are other emotions in similar vein about other things in the house, novels that I don't need to read again which I enjoyed, some of the children's books. Not all but just some of these things can go.
I think you can just make a balance sheet in your mind. Those possessions versus the ways I will use the space, tidiness, freedom, cleanliness that will follow from decluttering.
I feel like a hoarder, but when I think of it I have actually successfully decluttered, sylvanians, Barbies, fancy dress, garages, castles, various items of clothing that I didn't fit into but meant a lot to me memory wise, all sorts of just in case craft materials and haberdashery, clothes that I could have cut up and turned into new clothes, paper patterns, knitting wool, magazines full of interesting articles, scrapbooks full of cookery articles. And more. I don't miss them. I have them in my mind as pleasures that fulfilled me at the time, but now over. Like a holiday you enjoy and keep the memory of. I have to work hard to keep the balance, and I am still working at it. The things I recycle, chuck make space for the things that I really value, some material, some holistic. Imagine if someone gave you the entire contents of John Lewis. None of it would really be rubbish would it, but you couldn't physically fit it in your house? You would have to make a decision to give most of it back.
It is a struggle, no-one can tell you it isn't but you have to be brave. It probably represents £500 of actual "stuff" if you were to buy it again from ebay. Which you probably won't so it isn't real money you have lost. You have to decide if the price is worth losing the use of that room.