When a 6-year-old cheats at cards
Every 6-year-old cheats -- or thinks about it. Cheating is a particular specialty of this age group.
My theory is that they are both learning how games work and also exploring how they can manipulate cards, pieces and people.
I still have flashbacks to a fateful game of Candy Land where my pint-sized opponent cheated and I reacted basically as you did -- the grown-up equivalent of overturning the board and stomping away.
Childhood cheating presents the ultimate "teachable moment" for an adult. It is right to confront a cheater -- but after the confrontation you should display the maturity to demonstrate how much fun it is to play (and perhaps even win) honestly.
I agree with your friend who suggested keeping your cool and playing the game again, properly.

Sarra Sounds Off, Season 3, Ep 3: Top football teams in action, fantasy update and plays of the week Gregg Sarra sounds off on the Northport and Half Hollow Hills East matchup, plus Tess Ferguson has an update on the high school fantasy football standings and Jared Vailuzzi has the plays of the week.