Shanna Moakler Says Travis Barker Was Trashing Her Online When Together

Shanna Moakler ain't just a scorned ex-wife, she's a heartbroken one ... reflecting on the one moment she was utterly blindsided by Travis Barker -- while coming for the Kardashians yet again.

The ex-Miss USA is appearing on a new episode of Bunnie XO's "Dumb Blonde" podcast -- and in some teaser clips released ... Shanna claims she saw something that turned her world upside down -- this while setting up a video call on the drummer's computer as he underwent a blood transfusion at a burns unit after his 2008 plane crash.

She says she not only saw emails from loads of women ... but saw he was trashing her online and leaving nasty comments about what a shitty and terrible mother she was.

Shanna immediately left the hospital and cried in her mother's arms for hours ... unable to wrap her head around her then-husband trolling her. It's not exactly clear how she pieced together Travis' alleged bashing -- but in any case, she seems certain it was him.

Now, Shanna also slams the Kardashians in the podcast -- though it's nothing new as she's frequently made her distaste for Travis' new wife, Kourtney, loud and clear.

In her latest rant, she doubles down on disliking the family ... insisting she's not in the minority 'cause there are loads of people 'who don't watch the show and don't give a f*** what Kim's doing with her a**." Nothing new there, Shanna stays hatin' on them.