Chris Christie -- I Won't Root for the Nets ... They Betrayed New Jersey!!

Chris Christie is a fan scorned ... telling TMZ Sports he's still bitter at the Nets for ditching the Garden State for Brooklyn -- and that's why he WON'T be rooting for 'em in Game 7 today.

The Governor was leaving the White House Correspondent's Dinner in D.C. last night when asked if he still had even the tiniest bit of love in his heart for the former N.J. squad.