7:26 AM PT -- Etty Lau Farrell, wife of Perry Ferrell, shared her account of what happened prior to the stage brawl and the aftermath ... and she also is shading Eric Avery big time.

Basically ... she claims tension and animosity between the members has been building for a while ... and it came to a boil on stage Friday night in spectacular, albeit sad, fashion.

In the aftermath of the fight ... Perry "was a crazed beast for the next half an hour - he finally did not calm down, but did break down and cried and cried." She also shaded Eric ... claiming he "took advantage of the situation and got in a few cheap shots on Perry."

Jane's Addiction's Friday concert turned into a full-scale disaster after the band's two most famous members got into a fight in front of their Massachusetts audience.

Lead singer Perry Farrell went toe-to-toe with guitarist Dave Navarro onstage at Leader Bank Pavilion in Boston on Friday night – and it was all caught on video obtained by TMZ.

Check it out ... Dave was cranking out his electric guitar solo as Perry yelled angrily into the mic at the crowd.

Then Perry turned his rage on Dave, walking over to him and giving him a body check.  As the two exchanged words, Perry got in Dave's face, causing him to backpedal. Perry then threw a punch, but only hit Dave's guitar.

A man moved between them as Perry charged at Dave. Several members of the road crew jumped in and dragged Perry across the stage away from Dave.

We're told the situation was brewing all night ... While Perry's voice seemed fine, he was singing verses over and over again, pissing off his bandmates.

We've reached out to Jane's Addiction for comment ... so far no word back.