On the first point, you didn’t have to send him to Stanford for four years. If you’d qualified for the assistance, Stanford has extraordinarily generous student grant programs — not simply loans. If he was smart enough to get into Stanford, he likely would have qualified for full scholarship at other schools.
Regarding law school, as you also likely well know, nearly every school has a full tuition forgiveness program for students entering non-profit or social enterprise fields — all the info is right here for UC Davis. So if he (or you) are paying for that, you shouldn’t be.