Elle King Says Traumatic Incident Led to Disastrous Dolly Parton Tribute

Elle King's finally addressing her flubbed Dolly Parton performance in full ... chalking up the alcohol-infused moment to dealing with difficult issues in her life -- and, praising DP's grace.

The singer hopped on Chelsea Handler's podcast "Dear Chelsea" when she ruminated on the disastrous January performance ... calling the incident a huge mistake and diving into the lead-up to the show.

EK says she'd been going through something major at the time ... and the day of the performance was significant in whatever this major trauma was. She didn't get into detail about what exactly was troubling her ... but whatever it was caused her PTSD, she says.

Anyway, King also says she hadn't eaten or slept for days ahead of the show and after the first performance went well, she took one shot too many and completely disassociated, not remembering much. She says she remembers waking up in the dressing room, sobbing.

Elle goes on to say she sent out handwritten apologies to the Grand Ole Opry -- the venue -- and to Dolly herself ... who called Elle and made her feel better about the incident.

As we reported ... Elle hopped onstage at the legendary Nashville music venue hammered and forgot the lyrics to one of Dolly's songs. She used profane language throughout her cameo onstage too.

While Dolly's sister Stella blasted King, Parton herself spoke publicly in the aftermath and asked people to take it easy on King -- a classy move from the Queen, no doubt ... and something Elle appreciates now.