The incident you may be thinking of happened in Mockingjay Part 2, where Peeta, brainwashed and manipulated by the Capitol, attempts to strangle Katniss. However, he does not actually choke her.
This is a crucial moment in the story, as it highlights the extent of the Capitol's control over Peeta and the danger he poses to Katniss. It also shows the depth of Katniss's love and loyalty, as she struggles to protect him and bring back the Peeta she knew.