Shanna Moakler ain't sparing any of her exes ... blasting Oscar De La Hoya over how their relationship ended.
The former Miss USA claims she was blindsided after watching Oscar on TV attending the Latin Grammy Awards in L.A. with his now ex-wife Millie ... telling Bunnie XO's on her 'Dumb Blonde' Podcast he told her he was going to NYC for a work trip at the time.
She says a lawyer came to her Bel-Air mansion the next day .