Alanis Morissette says Ben Affleck told her to "lead" with her sexuality ... and she's still pissed enough about it to share a violent video of the dude onstage.

The rocker played a show in Los Angeles as part of her "Butterfly with a Machete: A Rock Traumedy" residency ... when she started talking about sexuality and relationships.

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At one point in her diatribe, Alanis says, "I’ve even had a guy ask me why I didn’t lead with my sexuality. Thank you, Ben Affleck.”

She then shared a clip from the movie "Dogma" -- which they both appeared in back in 1999 -- where Alanis, playing God, makes Ben's character's head explode, splattering blood and brain tissue everywhere.

It's unclear if Ben made the comment while shooting "Dogma" or at some other time ... we've reached out to his camp for clarification.

Alanis came out publicly as pansexual recently ... revealing her sexuality during a conversation on Tig Notaro, Fortune Feimster and Mae Martin's "Handsome" podcast.

Alanis' 4-night residency ended Wednesday night ... but Ben oughta know Alanis' animosity ain't ending anytime soon.