Floyd Mayweather -- My Ex's Abortion Is Fair Game ... We're Too Famous for Privacy

Floyd Mayweather is firing back at his ex-fiancee Shantel Jackson -- claiming he did NOT violate her right to privacy by discussing her abortion in detail on social media ... because their relationship was for public consumption anyway.

As we previously reported, Jackson sued Mayweather earlier this year for a bunch of different reasons -- including assault, battery, defamation, invasion of privacy and more.

Now, Floyd is trying to get the several claims dismissed -- and in new legal docs, he focused on her claim that he violated her right to privacy. He starts off his argument in the most Mayweather way possible:

"At age 37 I am an undefeated boxer. I have been the world champion in five different weight divisions."

He goes on to explain that when he met Jackson, "she asked me to help her become famous" ... and stated that her only semblance of fame was appearing in 7 music videos.

Floyd says he used his celebrity to help build her up -- and says they became so famous, people were interested in every aspect of their relationship ... including the breakup.

Which is why Floyd says he went to social media earlier this year and told the world he ended things with Shantel because she had an abortion behind his back.

"Both parties are public figures. Abortion is a public issue," Mayweather states in the docs.

He adds, "A public figure involved with another public figure in a public relationship can expect publicity, not privacy, about why it ends."

Mayweather wants the suit thrown out asap. A judge has yet to rule.