Summarised backstory first -
Married for 21 years and together 23/24 years. I am almost 47 Y/o. I am the higher earner of the two of us though we both earn decently - My only gap in work being a year Mat break 15 years ago. No second child mainly cos he is very tight fisted with money , even mine. I have always compromised and led a simple life - no fancy holidays etc , no fancy eating out or splurges with shopping. My only 'extravagance' from his perspective is I wanted our son to go a fee paying school and he does. Both our mortgage and DS school fees as well council tax, utilities, both phones go from my account that he also has a card to. His salary goes to another account that he saves , as he says, for 'our' retirement - he does afford himself little treats from there. He buys the groceries from there for us. He doesnt like eating out.
My mother has willed her house to me and is now almost 70. Last year she had rot and flooding in one part of the house and her situation was pitiable, staying at a friends house as the roof in one part of the house was horrific. She lives comfortably on a pension and some savings in the bank but didnt have enough to rebuild or even renovate parts of the house and it was ancient/crumbling. She thought about selling it to a small developer who would build it up as 2 units and then sell one and give her one unit. which I would get in future was her plan, it was H who said the developer seems very dodgy blah blah blah , finally long story short - I paid the money for the renovation and repairs which was under 50K (with him okaying it at the time) - now he says my mother should pay him 300 GBP every month for the 50K since he refused to free up any liquidity for me to have the 50k ( we have other assets we could have sold, and I had other plans for financing it myself) but he insisted at the time he pay the 50K from his severance pay he got last year (he got a new job immediately) - I told him I will give him the 300 GBP but he insists my mother pay it out of her monthly pension and savings. presumably my money is all his anyway and not he wants more. AIBU ?