The magic in that $20 seems to have gotten lost, let's help you find it again. REGARDLESS of what the person did, you helped someone who was in need. NEVER EVER close your heart to those in need, even if you get scammed once in a while.
Even if there is no heaven or hell (although I still beleive) you felt GOOD, right? That's the gift of the $20. Let it go at that. Merry Christmas!!!!