You ask the financial aid office if they can reconsider your aid package given your family’s changed circumstances. Some places won’t look at aid offers from other institutions, so ask in the Financial Aid Forum about MIT vs. Yale. Someone there might know.
$20k total for a year is about $7,500 less than what UM-CP would be with on-campus housing in-state without aid. So in that sense, MIT’s package is a good one. Whether you and your family can come up with $20k is another story. We couldn’t when Happykid was headed into college, so she started at the local CC then finished at Towson.