Institute a Suit against him with an Interim Application for attachment of his lands before judgment.
It may take even twenty years for you to recover money if he's adamant. You'll recover money. At least your children will. His death won't end up inabatement
You'll recover less than half the amount you spend. Your money and its interest will be gone.
He'll suffer double than what you suffer.
It's a pity passing a Decree and deciding an Execution Petition on a Promissory Note is so long a process with the matter being as simple as it is.