Per a report from TMZ, Rob is "furious" with Thompson and thinks of the Cavs big man as "an assh--e."
Last month, Shanti Das and Kelly McLaughlin of the Daily Mail reported videos recorded at a nightclub in Manhattan appeared to show Thompson leaning in to kiss another woman.
Despite the scandal, Thompson and Kardashian are reportedly still a couple, with TMZ obtaining footage of them eating together at a restaurant in Cleveland on May 4.
She gave birth to the couple's daughter, True Thompson, on April 12. Thompson was present in the delivery room.
Thompson and Kardashian began dating in September 2016. She was previously married to NBA star Lamar Odom from 2009 to 2016.