That's a tough one and I'm in the same situation. I've helped a few widows of close friends liquidate collections. It's a lot of work, takes time to get fair value and I don't want to put others in that position. My wife indulges me, but isn't really interested in my stuff.
I know you're fairly well informed, so no one knows as much about your goodies as you. I've been trying to thin my collection, but it's difficult and I seem to have a hard time not adding new found treasures.
I focus on local collector shows and try to decide what I can live without. I try to pick higher dollar items that I don't use and are redundant to my collection.
A couple of examples...
I've owned a Belgian FN/LAR match for decades. It's a great shooter and a superb battle rifle. I picked up a Belgian folding stock paratrooper a few years ago, but it just sat in the safe. I showed the folder to friend/collector and he paid my price on the spot.
I like the .41 Mag cartridge. I purchased an early 3-screw Ruger Blackhawk from a friends estate. I liked it enough to get a basketweave Lawrence western belt and holster for it and a fancy Silversmith buckle. I also had a nickel S&W Model 58 that was new in the box with all. I had no intention of ever shooting the 58, so I priced it at current market value and put it out at a local show. It was gone within the first hour.
I know most of us spent years accumulating our collections, but we can't take them with us. If you don't have heirs who would really appreciate them, thin the herd.