Khloe Kardashian’s ex Tristan Thompson is making headlines again and unfortunately for all involved, it appears the NBA player, who was once dubbed ‘Tristan Third Trimester Thompson’ for cheating on Kardashian while she was pregnant with the couple’s daughter, hasn’t changed his ways. 

In fact, not only has Thompson continued cheating on Kardashian, but he got another woman, personal trainer Maralee Nichols, pregnant in the process. This week, Nichols, who gave birth to a baby boy last week, sued Thompson for child support, saying the pair conceived a child together in March on Thompson’s 30th birthday. 

In the court documents obtained by PEOPLE, Thompson confessed to having sex with Nichols on at least one occasion, something which naturally has upset Kardashian, who was dating him during his birthday, at the time of the affair.

LOS ANGELES, CA – JANUARY 13: Khloe Kardashian and Tristan Thompson are seen on January 13, 2019 in Los Angeles, CA. (Photo by Hollywood To You/Star Max/GC Images)

“Khloé was upset to find out that he cheated again,” a source told PEOPLE. “She just can’t believe that he is going to be a dad again. It’s just a sad situation to her.”

When Thompson initially cheated on Kardashian during her pregnancy—and then again with Kylie Jenner’s best friend Jordyn Woods—the source notes Kardashian’s friends encouraged her “over and over again” not to take Thompson back. Ultimately, Kardashian ignored the advice and remained by Thompson’s side “because she always believed that he would change” and wanted to keep the family intact for their daughter, True.

During quarantine, it appeared Kardashian and Thompson’s relationship was stronger than ever, something PEOPLE’s source confirms. They were “doing great” while quarantined together and even considered having another child together through  a surrogate at one point. But Kardashian reportedly “knew things would change” as soon as Thompson returned to NBA. “She was just hopeful that he would stay faithful and loyal to her,” the insider noted, adding, “Khloe’s family always tried to support her. They always treated Tristan well even after he broke Khloe’s heart multiple times.”

Thompson and Kardashian have been on and off for several years, and most recently split in June, which was the same month Nichols filed her initial lawsuit requesting “reasonable expenses of pregnancy and birth” as well as legal fees from Thompson. According to E! News, she is also seeking full legal and physical custody of her son, while requesting that Thompson be granted visitation rights.