I don't know who said it (?Frank Sinatra), but the saying "Success is the best revenge" comes to mind.
And so does a quote from one of my kids' favorite movies, Cool Runnings. Darice Banyon asks Irving Blitzer why he cheated in the Olympic Games. And Irving says something about he thought winning was everything, but then he tells Darice what he learned was, "If you're not a winner without it [a gold medal], you'll never be one with it".
Sure it's disappointing to not get chosen for something you wanted. But the road of life is full of twists and turns that take us to some surprising places, some of which we had no intention of going. That doesn't make them less worthwhile necessarily, just different.
Be proud of the degree you earned. Go out now and do what you know and love. And if it's meant to be that someday you get into the MFA program, then you will. In the meantime, prove to yourself how good you are, MFA or No MFA.