The ex-Green Bay Packer really pissed off his ex, Courtney Finley, with comments he made on social media and TMZ Sports ... when he said the national anthem protests are more about self-promotion than social justice.

Courtney, who is white, blasted the guy in a scathing Twitter post saying ...

"This serves as a reminder @jermichaelf88 in case you have forgotten; you are black."

"The athletes (foremost people) you are telling to sit down (or stand) and shut up are the very men that are protesting for your safety and equality in a country that has nearly revoked that right based on your skin color."

"As a biracial mother of 4 black boys, that have been left to be raised by a single mother, I have deep and desperate gratitude for those that use their platform to fight for our community's justice, safety, & equality."

Courtney says Jermichael's comments are "absurd" and "offensive" -- adding, "Don't be so pathetically thirsty for attention that you choose to devalue another man's motives."

"Don't choose to be so insulting and imply professional athletes have no place in changing the world."

"Most importantly, don't forget to look in the mirror and see that you too are black and have an obligation to derail racism as best you can for yourself and others."

"If you don't want to be part of the resolution to the racial inequalities in this country that's on you, but for the sake of our 4 sons, don't be part of the problem. I pray you will reevaluate your stance."