Elon Musk's First Wife Blasts Him Over Failed Marriage

Elon Musk's first wife, Justine Wilson, says their marriage was super toxic ... she claims he made her feel "insignificant" throughout their relationship -- as if she was just his employee!

Justine said in the new "Musk" documentary ... "I learned the term 'gaslighting' through my relationship with Elon."

Elon's first wife -- who welcomed six kids with the Tesla CEO, including daughter Nevada, who died from SIDS at 10 weeks -- claimed that he told her, "I am the alpha in this relationship," as they danced at their wedding.

She added ... "He was constantly remarking on the ways he found me lacking."

Elon's got a few exes dragging him in the new documentary, which premiered Tuesday at the Venice Film Festival.

Former flame Ashley St. Clair claims she turned down a $40 million NDA offer so she could participate in the doc.

She said she wanted to set an example for her kids that speaking truth to power doesn't have a price tag.

However, the SpaceX founder called BS on her remarks.

Elon told us ... "She was never offered that and has a history of making false claims."