Ashley St. Clair Says She Rejected Elon Musk's $40 Million NDA

Ashley St. Clair is spilling ALL the tea about how she flat-out declined ex Elon Musk's alleged $40 million NDA offer ... and she says it was all about being able to talk freely about their rollercoaster relationship.

Ashley -- who shares a son, Romulus, with the Tesla CEO -- opened up at the Venice Film Festival Tuesday about her decision to reject the NDA ... she says she turned it down so she could participate in the new documentary, "Musk."

According to Variety, she dished to reporters ... "I want to set the example for my kids that you should never take being materially comfortable over speaking the truth."

This isn't the first time she's gotten candid about her former romance with the tech mogul.

As we previously reported in June ... Ashley revealed on Don Lemon's podcast that Elon shot his shot by sliding into her X messages.

What followed was a whirlwind romance that resulted in the birth of Romulus ... before the two former lovers became locked in a bitter ongoing custody battle.

In addition to refusing to ink an NDA, Ashley told Don she never signed any paperwork ... despite the fact that she says some of her pals had to sign docs just to enter the SpaceX founder's home.