By Alex Dobuzinskis
LOS ANGELES, Sept 4 (Reuters) - Boxer Floyd Mayweather Jr.'s ex-fiancee filed a lawsuit on Thursday accusing him of humiliating her after their breakup by posting online a copy of a sonogram from when she was pregnant with twins and saying she had an abortion.
The lawsuit filed by Shantel Jackson, 29, in Los Angeles Superior Court came little more than a week before the undefeated welterweight's Sept. 13 rematch against Marcos Maidana.
Mayweather, 37, who served two months in jail in 2012 for domestic violence against another ex-girlfriend, Josie Harris, and verbal threats against two of their children, is widely regarded as the world's best pound-for-pound boxer. He has held multiple world titles.
The legal action brought by Jackson, which says Mayweather violated her privacy, assaulted her and virtually imprisoned her at his Las Vegas home, threatens to distract from the athlete's return to the limelight.
The former model and actress met Mayweather in 2006 when she worked as a hostess in Atlanta, and they later began dating and were engaged, her attorney, Gloria Allred, told a news conference in Los Angeles.
Jackson stood by him through the domestic violence case and visited him in jail. Then after he was released in August 2012, he physically assaulted her, Allred said.
During the on-again off-again relationship that followed, Mayweather sent a private jet to bring Jackson from Los Angeles, where she lived, to join him in Las Vegas and showered her with Hermes handbags, the attorney said.
At one point, when Jackson was in Los Angeles and refused to move to Las Vegas, Mayweather wrote on Facebook and Instagram that they broke up because she had an abortion and he was "totally against killing babies," and he posted a sonogram of the twin fetuses he fathered, according to the lawsuit.
"I have been embarrassed and humiliated more than I can ever imagine by Floyd, whom I once called my best friend and fiance," a tearful Jackson told reporters.
Allred declined to say if Jackson had an abortion, but acknowledged her pregnancy ended in January.
Representatives for Mayweather did not return calls.
The lawsuit also accused Mayweather of arranging to have over $1 million worth of Jackson's property taken from a storage unit where she put such items as bags and shoes.
Forbes ranks Mayweather as one of the top-earning athletes of 2014, with estimated income of over $100 million. (Reporting by Alex Dobuzinskis; Editing by Cynthia Johnston and Peter Cooney)