The album's lead single "Hold It Against Me" debuted at number-one on the Billboard Hot 100, becoming Spears's fourth number-one single on the chart and making her the second artist in history to have two consecutive singles debut at number one, after Mariah Carey. The second single "Till the World Ends" peaked at number three on the Billboard Hot 100 in May, while the third single "I Wanna Go" reached number seven in August. Femme Fatale became Spears's first album in which three of its songs reached the top ten of the chart. The fourth and final single "Criminal" was released in September 2011. The music video caused controversy when British politicians criticized Spears for using replica guns while filming the video in an area of London that had been badly affected by the 2011 England riots. Spears's management briefly responded, stating, "The video is a fantasy story featuring Britney's boyfriend, Jason Trawick, which literally plays out the lyrics of a song written three years before the riots ever happened." In April 2011, Spears appeared in a remix of Rihanna's song "S&M". It reached number one in the US later in the month, giving Spears her fifth number one on the chart. On Billboard's 2011 Year-End list, Spears was ranked number fourteen on the Artists of the Year, thirty-two on Billboard 200 artists and ten on Billboard Hot 100 artists. Spears co-wrote "Whiplash", a song from American pop rock band Selena Gomez & the Scene' third album When the Sun Goes Down.In June 2011, Spears embarked on the Femme Fatale Tour. The first ten dates of the tour grossed $6.2 million, landing the fifty-fifth spot on Pollstar's Top 100 North American Tours list for the half-way point of the year. The tour ended on December 10, 2011 in Puerto Rico after 79 performances. A DVD of the tour was released in November 2011. In August 2011, Spears received the Michael Jackson Video Vanguard Award at the 2011 MTV Video Music Awards. The next month, she released her second remix album, B in the Mix: The Remixes Vol. 2. In December, Spears became engaged to her long-time boyfriend Jason Trawick, who had formerly been her agent. Trawick became a co-conservator of Spears, alongside her father, in April 2012. In January 2013, Spears and Trawick ended their engagement. Trawick was also removed as Spears's co-conservator, restoring her father as the sole conservator.In May 2012, Spears was hired to replace Nicole Scherzinger as a judge for the second season of the U.S. version of The X Factor, joining Simon Cowell, L.A. Reid and fellow new judge Demi Lovato, who replaced Paula Abdul. With a reported salary of $15 million, she became the highest-paid judge on a singing competition series in television history. However, Katy Perry broke her record in 2018 after Perry was signed for a $25-million salary to serve as a judge on ABC's revival of American Idol. She mentored the Teens category; her final act, Carly Rose Sonenclar, was named the runner-up of the season. Spears did not return for the show's third season and her spot was filled by Kelly Rowland. Spears was featured on will.i.am's "Scream & Shout", which was released as a single from his fourth studio album, #willpower (2013). The song later became Spears's sixth number one single on the UK Singles Chart and peaked at No. 3 on US Billboard Hot 100. Scream & Shout was among the best selling songs of 2012 and 2013 with denoting sales of over 8.1 million worldwide, the accompanying music video was the third-most viewed video in 2013 on VEVO despite the video being released in 2012. In December, Forbes magazine named her music's top-earning woman of 2012, with estimated earnings of $58 million.

Question: when did Spears end her engagement?
Answer: January 2013