What does Richard tell Kahlan about why he won't wear a collar?

Richard explains to Kahlan that the reason he won't ever wear a collar again is because of a Mord-Sith that captured Richard. Mord-Sith are women that use magical collars to control their captives and cause them excruciating pain. Richard tells Kahlan everything that the Mord-Sith, Denna, made him do.