We did the same thing and got a storage unit (though it was my wife's idea, I heartily concurred)! Though to make matters worse, she's quite the "pack rat", having kept stuff from when her 27-year old was a baby. And not just baby things. We're talking whatever was in the house stuff! Now, just over a year later she's saying things like "I wish we could just load up a U-Haul and take all the stuff in storage to the girls..." Music to my ears!
After we'd made the decision to liveaboard, we went through the process of thinking 'what do we keep?' or more to the point, 'how do we decide what to offload?'
After much thought and discussion (argument?) we arrived at the following formula,
Heirlooms: The items that had been in the family for generations we'd put into long term storage to go to our children on our death. We'd not give it now just in case we didn't like living aboard and bought a house. We'd know this in 2/3 years.
The rest of the furniture: Auction, ebay, charity shops, give away. All of it. Literally.
Boxes of 'stuff' in the attic: This was the last element. The many boxes we'd filled and stored in the attic over the years, many of which had been passed down to us by parents, some of which had been passed to them by their parents and so on. Some we'd never even opened. For this we used the argument, 'if we dropped dead tomorrow, what would the children do with it? How would they know what's valuable or of any use to them?'
It took us a year, but we attacked the task box by box, only keeping 'what's valuable or of any use to them'. That reduced the huge mound to about 10 boxes, each labelled and documented so they could make well founded decisions when the time came.
This also went into long term storage.
Finally, it was the 'few bits we'd like to have available' which included boat spares, some of my wife's clothes and so on, for which we took a self store which we use regularly.
And that was that. From a six bed house to a Fleming, with a small longterm store for heirlooms and a self store for 'everyday' items we can't keep on the boat.
How did we feel doing it? At times, heart torn. How do we feel now? Relief.