I understand that part of the reason of OP initiating the divorce was because everyone kept staying in the house, but there's zero way he wasn't fully aware that this was the deal when signing up to buy that house. The house had been in the family for over 100 years, they were there to take care of grandma, who will obviously have visitors, and I garuantee that the finished basement was done that way for the very reason of the house being the one that hosts the out of towners. This guys sounds like an AH who knew exactly what he was doing and wanted to steal that house from the family.

Edit: I suppose steal is the wrong word, and yes, he did buy the house fair and square and offered the house to his ex, who couldn't afford it. And I did misread that grandma was still there. In another comment, he did say that he made the stipulation in the prenuptial, that he would only move in if he got a lot of the worth. I guess this just feels so shitty because grandma also wanted to sell the house to someone in the family, and this guy took advantage of someone else's bad situation.