Six years ago, I was so overwhelmed by my DHs "hobby stuff" - antique radios, 45 record players, antique cars - that I literally moved out of state to get away from it. (I worked from home, so location was 100% up to me.)
I did not move to get away from DH, mind you, I love him and will until the end of our days together. But the 'stuff' was suffocating me. There was absolutely no room for my stuff (not that I had much). We were living in a 5 bedroom, two garage, 3 full bath house and the kids had moved out...
Initially, I rented a 2 bedroom apt. near the beach. Tiny kitchen, two small baths, living and dining area were also small. And, best of all, no clutter and no yard work! I LOVED IT! It literally took me 15 - 30 minutes to clean. My DH visited me frequently and was worried that I didn't love him because I seemed so much happier. I explained to him that HE was not the problem, his stuff was.
After 6 months, I decided I liked the location and could live there happily. He decided to join me. We bought a house. I wanted to DOWNSIZE, he wanted a big fancy house with a large yard. Can't figure out why he wanted a big yard - it's a ton of work! We "compromised" on a 3 bedroom house with two attached garages and a detached 3 car garage that had AC/heat and a bath. I told him that NONE of his hobby stuff could come in the house unless I pre-approved it. He agreed. We live happily there, thank God.
The 3 car garage is getting 'stuffed' - but my house is not.
He refuses to sell our former home because it has so much of his stuff in it. We rent the upstairs out to my sister (the rent pays the taxes) and use the basement when we are in town. It's kind of handy to have it, but the yard is going to hell and he doesn't want to maintain the house. We could sell it and buy a smaller town house, or renovate the income property we own a mile away and live in it, but no, he can't do that.
Getting him to clean out that house is going to be hell. What amazes me is that he is extremely 'careful' with money, but doesn't recognize the the financial drain of maintaining two houses.
So take the advice of those who responded to your post. Be ruthless. You don't need to keep everything you accumulated over the years. Keep the really precious things you have, let the others go. So much stuff is familiar and comforting, but can become emotionally paralyzing.
Above all, make up your mind to be happy in your new home, and you will be!