It's one strike and you're out when it comes to domestic violence ... so says the GF of ex-NFL linebacker Keith Mitchell ... who says she dumped him after he got violent, despite the fact she's pregnant with his child.
TMZ Sports broke the story ... the former New Orleans Saints linebacker was arrested earlier this month after cops say they noticed a bruise on his GF's face following a domestic incident.
We spoke with the woman at the center of the incident, Sasha Gradiva (who gave us permission to use her name and image) ... and she says there's no 2nd chance when it comes to violence.
Gradiva says she was shocked by Mitchell's behavior -- considering he's now a famous yoga instructor and should be able to channel his anger in a non-violent way.
"It was not an easy choice to call the police," Gradiva says ... "But I don't think his actions should be tolerated under any condition."
It's especially difficult for Sasha since she's due to give birth any day -- and the last thing she wanted was to have to separate with the father of her child -- but she felt he gave her no choice.
"I have to think about myself and my daughter ... I want her to grow up in a healthy environment."
We reached out to Mitchell for comment -- so far, no word back.